diff --git a/README.md b/README.md
index 6cd9203..c5aa5ad 100644
--- a/README.md
+++ b/README.md
@@ -8,7 +8,7 @@ This is a rewrite of the game [Blues Brothers](https://www.mobygames.com/game/bl
 
 ## Requirements
 
-The game data files of the DOS version (retail or demo) are required.
+The game data files of the DOS or Amiga version are required.
 
 ```
 *.BIN, *.CK1, *.CK2, *.SQL, *.SQV, *.SQZ
diff --git a/game.c b/game.c
index de26590..18ae693 100644
--- a/game.c
+++ b/game.c
@@ -24,12 +24,12 @@ void update_input() {
 	g_vars.inp_key_up = ((g_sys.input.direction & INPUT_DIRECTION_UP) != 0) || g_vars.inp_keyboard[0x48] || g_vars.inp_keyboard[0x7C];
 	g_vars.inp_key_down = ((g_sys.input.direction & INPUT_DIRECTION_DOWN) != 0) || g_vars.inp_keyboard[0x50] || g_vars.inp_keyboard[0x7B];
 	g_vars.inp_key_space = g_sys.input.space || g_vars.inp_keyboard[0x39] || g_vars.inp_keyboard[0x77];
-	g_vars.inp_key_tab = g_vars.inp_keyboard[0xF] || g_vars.inp_keyboard[0x78];
+	// g_vars.inp_key_tab = g_vars.inp_keyboard[0xF] || g_vars.inp_keyboard[0x78];
 }
 
 void do_title_screen() {
 	const uint32_t timestamp = g_sys.get_timestamp() + 20 * 1000;
-	load_img(g_options.amiga_data ? "blues.lbm" : "pres.sqz", GAME_SCREEN_W);
+	load_img(g_res.amiga_data ? "blues.lbm" : "pres.sqz", GAME_SCREEN_W);
 	fade_in_palette();
 	do {
 		update_input();
@@ -50,11 +50,11 @@ void do_select_player() {
 	int frame2 = 1;
 	const int color_rgb = 2;
 	const int colors_count = 25;
-	load_img(g_options.amiga_data ? "choix.lbm" : "choix.sqz", GAME_SCREEN_W);
+	load_img(g_res.amiga_data ? "choix.lbm" : "choix.sqz", GAME_SCREEN_W);
 	screen_load_graphics();
 	screen_clear_sprites();
 	do {
-		screen_unk4();
+		screen_copy_img();
 		update_input();
 		const uint32_t timestamp = g_sys.get_timestamp();
 		switch (state) {
@@ -181,13 +181,11 @@ void do_select_player() {
 			}
 			continue;
 		}
-		screen_clear_last_sprite();
 		screen_redraw_sprites();
 		screen_flip();
 		screen_vsync();
 		const int diff = (timestamp + (1000 / 30)) - g_sys.get_timestamp();
 		g_sys.sleep(diff < 10 ? 10 : diff);
-		g_vars.screen_draw_offset ^= 0x2000;
 		screen_clear_sprites();
 		if (g_sys.input.space || g_vars.play_demo_flag) {
 			quit = 1;
@@ -196,12 +194,8 @@ void do_select_player() {
 }
 
 static void do_inter_screen_helper(int xpos, int ypos, int c) {
-	if (c != 0) {
-		g_vars.screen_draw_offset ^= 0x2000;
-	}
 	for (int i = 0; i < 40; ++i) {
 		screen_add_sprite(xpos + 20 - 1 - i, ypos - 20 + 1 + i, 125);
-		screen_clear_last_sprite();
 		screen_redraw_sprites();
 		if (c != 0) {
 			screen_vsync();
@@ -210,22 +204,18 @@ static void do_inter_screen_helper(int xpos, int ypos, int c) {
 	}
 	for (int i = 0; i < 40; ++i) {
 		screen_add_sprite(xpos - 20 + 1 + i, ypos - 20 + 1 + i, 125);
-		screen_clear_last_sprite();
 		screen_redraw_sprites();
 		if (c != 0) {
 			screen_vsync();
 		}
 		screen_clear_sprites();
 	}
-	if (c != 0) {
-		g_vars.screen_draw_offset ^= 0x2000;
-	}
 }
 
 static void do_inter_screen() {
 	static const uint8_t xpos[] = { 0xFA, 0x50, 0xF0, 0xC8, 0x50, 0x50 };
 	static const uint8_t ypos[] = { 0xAA, 0x37, 0x28, 0x5F, 0xA5, 0xAA };
-	load_img(g_options.amiga_data ? "inter.lbm" : "inter.sqz", GAME_SCREEN_W);
+	load_img(g_res.amiga_data ? "inter.lbm" : "inter.sqz", GAME_SCREEN_W);
 	g_vars.screen_draw_h = GAME_SCREEN_H - 1;
 	screen_clear_sprites();
 	if (g_vars.level > 1) {
@@ -240,16 +230,13 @@ static void do_inter_screen() {
 	if (g_vars.level > 0 && g_vars.level < MAX_LEVELS - 1) {
 		do_inter_screen_helper(xpos[g_vars.level - 1], ypos[g_vars.level - 1], 1);
 	}
-	g_vars.screen_draw_offset = 0x2000;
-	screen_do_transition2();
+	// screen_do_transition2();
 	screen_flip();
 	if (g_vars.level < MAX_LEVELS - 1) {
 		play_sound(SOUND_2);
 		screen_add_sprite(xpos[g_vars.level], ypos[g_vars.level], 126);
-		screen_clear_last_sprite();
 		screen_redraw_sprites();
 	}
-	g_vars.screen_draw_offset = 0x2000;
 	screen_flip();
 	const uint32_t timestamp = g_sys.get_timestamp() + 4 * 1000;
 	do {
@@ -263,17 +250,16 @@ static void do_inter_screen() {
 
 void game_main() {
 	play_music(0);
-	g_vars.screen_draw_offset = 0;
 	screen_init();
 	screen_flip();
 	g_vars.start_level = 0;
-	if (g_options.amiga_data) {
+	if (g_res.amiga_data) {
 		load_spr("sprite", g_res.spr_sqv, 0);
 		load_spr("objet", g_res.spr_sqv + SPRITE_SIZE, 101);
 	} else {
 		load_sqv("sprite.sqv", g_res.spr_sqv, 0);
 	}
-	if (g_options.amiga_status_bar) {
+	if (g_options.amiga_status_bar || g_res.amiga_data) {
 		uint16_t palette[16];
 		for (int i = 0; i < 16; ++i) {
 			assert(_colors_180_data[i * 2] == 0x180 + i * 2);
diff --git a/game.h b/game.h
index e09e178..3191105 100644
--- a/game.h
+++ b/game.h
@@ -10,6 +10,7 @@
 #define TILEMAP_OFFSET_Y  14
 #define TILEMAP_SCREEN_W  GAME_SCREEN_W
 #define TILEMAP_SCREEN_H (GAME_SCREEN_H - 40)
+#define TILEMAP_SCROLL_W  64
 
 #define PLAYER_JAKE   0
 #define PLAYER_ELWOOD 1
@@ -46,8 +47,8 @@ struct options_t {
 	int screen_h;
 	bool amiga_copper_bars;
 	bool amiga_colors;
-	bool amiga_data;
 	bool amiga_status_bar;
+	bool dos_scrolling;
 };
 
 extern struct options_t g_options;
@@ -150,12 +151,11 @@ struct vars_t {
 	int16_t level_xpos[MAX_OBJECTS];
 	int16_t level_ypos[MAX_OBJECTS];
 	int screen_tilemap_w, screen_tilemap_h;
-	int screen_tilemap_w16, screen_tilemap_h16;
 	int screen_tilemap_xorigin, screen_tilemap_yorigin;
 	int screen_tilemap_xoffset, screen_tilemap_yoffset;
 	int screen_tilemap_size_w, screen_tilemap_size_h;
-	int screen_scrolling_dirmask, screen_unk1;
-	int screen_draw_h, screen_draw_offset;
+	int screen_scrolling_dirmask;
+	int screen_draw_h;
 	int screen_tile_lut[256];
 	bool level_completed_flag;
 	bool play_level_flag;
@@ -167,17 +167,17 @@ struct vars_t {
 	bool play_demo_flag;
 	bool quit_level_flag;
 	bool two_players_flag;
+	bool switch_player_scrolling_flag;
 	int music_num;
 	uint8_t inp_keyboard[256];
-	int inp_key_space;
-	int inp_key_tab;
-	int inp_key_up;
-	int inp_key_down;
-	int inp_key_right;
-	int inp_key_left;
-	int inp_key_up_prev;
-	int inp_key_down_prev;
-	int inp_key_action;
+	bool inp_key_space;
+	bool inp_key_up;
+	bool inp_key_down;
+	bool inp_key_right;
+	bool inp_key_left;
+	bool inp_key_up_prev;
+	bool inp_key_down_prev;
+	bool inp_key_action;
 	struct door_t doors[MAX_DOORS];
 	struct object_t objects[MAX_OBJECTS];
 	int vinyls_count;
@@ -240,7 +240,6 @@ extern void	level_call_object_func(struct object_t *);
 extern void	screen_init();
 extern void	screen_clear_sprites();
 extern void	screen_add_sprite(int x, int y, int frame);
-extern void	screen_clear_last_sprite();
 extern void	screen_redraw_sprites();
 extern void	fade_in_palette();
 extern void	fade_out_palette();
@@ -248,13 +247,12 @@ extern void	screen_adjust_palette_color(int color, int b, int c);
 extern void	screen_vsync();
 extern void	screen_draw_frame(const uint8_t *frame, int fh, int fw, int x, int y);
 extern void	screen_flip();
-extern void	screen_unk4();
+extern void	screen_copy_img();
 extern void	screen_unk5();
-extern void	screen_unk6();
 extern void	screen_do_transition1(int a);
 extern void	screen_do_transition2();
 extern void	screen_clear(int a);
-extern void	screen_draw_tile(int tile, int dst, int type);
+extern void	screen_draw_tile(int tile, int type, int x, int y);
 extern void	screen_draw_number(int num, int x, int y, int color);
 extern void	screen_add_game_sprite1(int x, int y, int frame);
 extern void	screen_add_game_sprite2(int x, int y, int frame);
diff --git a/intern.h b/intern.h
index 9ae096d..6ea6678 100644
--- a/intern.h
+++ b/intern.h
@@ -9,15 +9,6 @@
 #include <string.h>
 #include <stdbool.h>
 
-#ifndef MIN
-#define MIN(a,b) ((a)<(b)?(a):(b))
-#endif
-#ifndef MAX
-#define MAX(a,b) ((a)>(b)?(a):(b))
-#endif
-#ifndef ABS
-#define ABS(a) (((a)<0)?(-(a)):(a))
-#endif
 #ifndef ARRAYSIZE
 #define ARRAYSIZE(a) (sizeof(a)/sizeof(a[0]))
 #endif
diff --git a/level.c b/level.c
index 9219bd0..f0b0656 100644
--- a/level.c
+++ b/level.c
@@ -60,7 +60,7 @@ static const struct {
 
 void load_level_data(int num) {
 	print_debug(DBG_GAME, "load_level_data num %d", num);
-	if (g_options.amiga_data) {
+	if (g_res.amiga_data) {
 		load_blk(_levels_amiga[num].blk);
 		read_file(_levels_amiga[num].tbl, g_res.sql, 0);
 		load_bin(_levels_amiga[num].bin);
@@ -68,7 +68,7 @@ void load_level_data(int num) {
 		// .avt
 		load_spr(_levels_amiga[num].ennemi, g_res.tmp, SPRITES_COUNT);
 	} else {
-		if (num == 0 && (g_res.flags & RESOURCE_FLAGS_DEMO)) { // DOS demo
+		if (num == 0 && g_res.dos_demo) {
 			load_ck("demomag.ck1", 0x6000);
 			load_ck("demomag.ck2", 0x8000);
 			load_sql("demomag.sql");
@@ -261,24 +261,21 @@ static void init_level() {
 }
 
 static void do_level_redraw_tilemap(int xpos, int ypos) {
-	const int w = TILEMAP_SCREEN_W / 16;
-	const int h = TILEMAP_SCREEN_H / 16;
-	int y = ypos >> 4;
-	int x = xpos >> 4;
-	for (int j = 0; j < h * 640; j += 640) {
-		const uint8_t *ptr = lookup_sql(x, y);
-		for (int i = 0; i < w * 2; i += 2) {
+	const int w = (TILEMAP_SCREEN_W / 16) + ((!g_options.dos_scrolling && (xpos & 15) != 0) ? 1 : 0);
+	const int h = (TILEMAP_SCREEN_H / 16) + ((!g_options.dos_scrolling && (ypos & 15) != 0) ? 1 : 0);
+	const int y = ypos >> 4;
+	const int x = xpos >> 4;
+	for (int j = 0; j < h; ++j) {
+		const uint8_t *ptr = lookup_sql(x, y + j);
+		for (int i = 0; i < w; ++i) {
 			const uint8_t num = *ptr++;
 			if (num >= 128) {
-				screen_draw_tile(g_vars.screen_tile_lut[num - 128], j + i, 4);
+				screen_draw_tile(g_vars.screen_tile_lut[num - 128], 4, i, j);
 			} else {
-				screen_draw_tile(g_vars.screen_tile_lut[num], j + i, 3);
+				screen_draw_tile(g_vars.screen_tile_lut[num], 3, i, j);
 			}
 		}
-		++y;
 	}
-	g_vars.screen_tilemap_xoffset = 0;
-	g_vars.screen_tilemap_yoffset = 0;
 	g_vars.screen_tilemap_size_w = w;
 	g_vars.screen_tilemap_size_h = h;
 }
@@ -292,11 +289,13 @@ static void do_level_update_tiles_anim() {
 			++p[0];
 		}
 	}
-	int y = g_vars.screen_tilemap_yorigin >> 4;
-	int x = g_vars.screen_tilemap_xorigin >> 4;
-	for (int j = 0; j < (TILEMAP_SCREEN_H / 16) * 640; j += 640) {
-		uint8_t *ptr = lookup_sql(x, y);
-		for (int i = 0; i < (TILEMAP_SCREEN_W / 16) * 2; i += 2, ++ptr) {
+	const int w = (TILEMAP_SCREEN_W / 16) + ((!g_options.dos_scrolling && (g_vars.screen_tilemap_xorigin & 15) != 0) ? 1 : 0);
+	const int h = (TILEMAP_SCREEN_H / 16) + ((!g_options.dos_scrolling && (g_vars.screen_tilemap_yorigin & 15) != 0) ? 1 : 0);
+	const int y = g_vars.screen_tilemap_yorigin >> 4;
+	const int x = g_vars.screen_tilemap_xorigin >> 4;
+	for (int j = 0; j < h; ++j) {
+		uint8_t *ptr = lookup_sql(x, y + j);
+		for (int i = 0; i < w; ++i, ++ptr) {
 			uint8_t num = *ptr;
 			struct trigger_t *t = &g_res.triggers[num];
 			const uint8_t *data = t->op_table2;
@@ -314,12 +313,11 @@ static void do_level_update_tiles_anim() {
 				t->unk16 = num;
 			}
 			if (num >= 128) {
-				screen_draw_tile(g_vars.screen_tile_lut[num - 128], j + i, 4);
+				screen_draw_tile(g_vars.screen_tile_lut[num - 128], 4, i, j);
 			} else {
-				screen_draw_tile(g_vars.screen_tile_lut[num], j + i, 3);
+				screen_draw_tile(g_vars.screen_tile_lut[num], 3, i, j);
 			}
 		}
-		++y;
 	}
 }
 
@@ -327,27 +325,58 @@ static void do_level_update_scrolling2() {
 	if (g_vars.screen_scrolling_dirmask & 2) {
 		if (g_vars.screen_tilemap_w * 16 - TILEMAP_SCREEN_W > g_vars.screen_tilemap_xorigin) {
 			g_vars.screen_tilemap_xorigin += 16;
-			// do_level_update_scrolling_left();
 		}
 	}
 	if (g_vars.screen_scrolling_dirmask & 1) {
 		if (g_vars.screen_tilemap_xorigin > 0) {
 			g_vars.screen_tilemap_xorigin -= 16;
-			// do_level_update_scrolling_right();
 		}
 	}
 	if (g_vars.screen_scrolling_dirmask & 8) {
 		if (g_vars.screen_tilemap_yorigin > 0) {
 			g_vars.screen_tilemap_yorigin -= 16;
-			// do_level_update_scrolling_top();
 		}
 	}
 	if (g_vars.screen_scrolling_dirmask & 4) {
 		if (g_vars.screen_tilemap_h - TILEMAP_SCREEN_H > g_vars.screen_tilemap_yorigin) {
 			g_vars.screen_tilemap_yorigin += 16;
-			// do_level_update_scrolling_bottom();
 		}
 	}
+	if (!g_options.dos_scrolling) {
+		const int x1 = TILEMAP_SCROLL_W * 2;
+		const int x2 = TILEMAP_SCREEN_W - TILEMAP_SCROLL_W * 2;
+		const struct object_t *obj = &g_vars.objects[OBJECT_NUM_PLAYER1];
+		if (obj->screen_xpos > x2) {
+			const int dx = obj->screen_xpos - x2;
+			g_vars.screen_tilemap_xorigin += dx;
+			if (g_vars.screen_tilemap_xorigin + TILEMAP_SCREEN_W > g_vars.screen_tilemap_w * 16) {
+				g_vars.screen_tilemap_xorigin = g_vars.screen_tilemap_w * 16 - TILEMAP_SCREEN_W;
+			}
+		} else if (obj->screen_xpos < x1) {
+			const int dx = obj->screen_xpos - x1;
+			g_vars.screen_tilemap_xorigin += dx;
+			if (g_vars.screen_tilemap_xorigin < 0) {
+				g_vars.screen_tilemap_xorigin = 0;
+			}
+		}
+		const int y1 = 64;
+		const int y2 = 144;
+		if (obj->screen_ypos > y2) {
+			const int dy = obj->screen_ypos - y2;
+			g_vars.screen_tilemap_yorigin += dy;
+			if (g_vars.screen_tilemap_yorigin + TILEMAP_SCREEN_H > g_vars.screen_tilemap_h) {
+				g_vars.screen_tilemap_yorigin = g_vars.screen_tilemap_h - TILEMAP_SCREEN_H;
+			}
+		} else if (obj->screen_ypos < y1) {
+			const int dy = obj->screen_ypos - y1;
+			g_vars.screen_tilemap_yorigin += dy;
+			if (g_vars.screen_tilemap_yorigin < 0) {
+				g_vars.screen_tilemap_yorigin = 0;
+			}
+		}
+		g_vars.screen_tilemap_xoffset = -(g_vars.screen_tilemap_xorigin & 15);
+		g_vars.screen_tilemap_yoffset = -(g_vars.screen_tilemap_yorigin & 15);
+	}
 	do_level_redraw_tilemap(g_vars.screen_tilemap_xorigin, g_vars.screen_tilemap_yorigin);
 	if ((g_vars.level_loop_counter & 3) == 0) {
 		do_level_update_tiles_anim();
@@ -376,7 +405,7 @@ static void do_level_add_sprite1_case0(struct object_t *obj) {
 	} else if (triggers_get_tile_type(obj->xpos16, obj->ypos16) == 4) {
 		anim_data = obj->animframes_ptr[28 / 4];
 	} else {
-		if (ABS(obj->yvelocity) > 10 && obj->yvelocity > 0) {
+		if (abs(obj->yvelocity) > 10 && obj->yvelocity > 0) {
 			anim_data = obj->animframes_ptr[112 / 4];
 		} else {
 			anim_data = obj->animframes_ptr[8 / 4];
@@ -447,7 +476,7 @@ static void do_level_add_sprite1_case1(struct object_t *obj) {
 			anim_data = obj->animframes_ptr[0];
 		}
 		if (obj->unk2D < 8) {
-			if (ABS(obj->xvelocity) > 8) {
+			if (abs(obj->xvelocity) > 8) {
 				anim_data = obj->animframes_ptr[24 / 4];
 			}
 		}
@@ -794,32 +823,35 @@ void do_level_update_tile(int x, int y, int num) {
 	uint8_t *ptr = lookup_sql(x, y);
 	*ptr = num;
 
+	const int tile_xpos = g_vars.screen_tilemap_xorigin >> 4;
+	const int tile_ypos = g_vars.screen_tilemap_yorigin >> 4;
+
 	const int w = (TILEMAP_SCREEN_W / 16) * 2;
-	int _si = x * 2 + g_vars.screen_tilemap_yoffset - (g_vars.screen_tilemap_xorigin >> 3);
+	int _si = (x + tile_xpos) * 2 + g_vars.screen_tilemap_xoffset;
 	if (_si > w - 2) {
 		_si -= w;
 	}
 	const int h = (TILEMAP_SCREEN_H / 16) * 640;
-	int _di = (y - (g_vars.screen_tilemap_yorigin >> 4)) * 640 + g_vars.screen_tilemap_xoffset;
+	int _di = (y - tile_ypos) * 640 + g_vars.screen_tilemap_yoffset;
 	if (_di > h - 640) {
 		_di -= h;
 	}
-	if ((g_vars.screen_tilemap_xorigin >> 4) > x) {
+	if (tile_xpos > x) {
 		return;
 	}
-	if ((g_vars.screen_tilemap_xorigin >> 4) + (TILEMAP_SCREEN_W / 16) <= x) {
+	if (tile_xpos + (TILEMAP_SCREEN_W / 16) <= x) {
 		return;
 	}
-	if ((g_vars.screen_tilemap_yorigin >> 4) > y) {
+	if (tile_ypos > y) {
 		return;
 	}
-	if ((g_vars.screen_tilemap_yorigin >> 4) + (TILEMAP_SCREEN_H / 16) <= y) {
+	if (tile_ypos + (TILEMAP_SCREEN_H / 16) <= y) {
 		return;
 	}
 	if (num >= 128) {
-		screen_draw_tile(g_vars.screen_tile_lut[num - 128], _di + _si, 4);
+		screen_draw_tile(g_vars.screen_tile_lut[num - 128], 4, _si / 2, _di / 640);
 	} else {
-		screen_draw_tile(g_vars.screen_tile_lut[num], _di + _si, 3);
+		screen_draw_tile(g_vars.screen_tile_lut[num], 3, _si / 2, _di / 640);
 	}
 }
 
@@ -983,28 +1015,16 @@ void do_level_update_panel_lifes(struct object_t *obj) {
 		static const uint16_t data[] = { 216, 232, 248, 264, 280, 296 };
 		for (int i = 0; i < obj->data51; ++i) {
 			screen_draw_frame(g_res.spr_frames[120 + i], 12, 16, data[i], 161);
-			g_vars.screen_draw_offset ^= 0x2000;
-			screen_draw_frame(g_res.spr_frames[120 + i], 12, 16, data[i], 161);
-			g_vars.screen_draw_offset ^= 0x2000;
 		}
 		for (int i = obj->data51; i < 5; ++i) {
 			screen_draw_frame(g_res.spr_frames[119 + i], 12, 16, data[i], 161);
-			g_vars.screen_draw_offset ^= 0x2000;
-			screen_draw_frame(g_res.spr_frames[119 + i], 12, 16, data[i], 161);
-			g_vars.screen_draw_offset ^= 0x2000;
 		}
 	} else {
 		static const uint8_t data[] = { 18, 21, 20, 19, 19, 19 };
 		if (obj->type == PLAYER_JAKE) {
 			screen_draw_frame(g_res.spr_frames[101 + data[obj->data51]], 12, 16, 80, 161);
-			g_vars.screen_draw_offset ^= 0x2000;
-			screen_draw_frame(g_res.spr_frames[101 + data[obj->data51]], 12, 16, 80, 161);
-			g_vars.screen_draw_offset ^= 0x2000;
 		} else {
 			screen_draw_frame(g_res.spr_frames[101 + data[obj->data51]], 12, 16, 248, 161);
-			g_vars.screen_draw_offset ^= 0x2000;
-			screen_draw_frame(g_res.spr_frames[101 + data[obj->data51]], 12, 16, 248, 161);
-			g_vars.screen_draw_offset ^= 0x2000;
 		}
 	}
 	if (obj->data51 == 0) { // health
@@ -1017,33 +1037,21 @@ void do_level_update_panel_lifes(struct object_t *obj) {
 				obj->data51 = 3;
 				do_level_update_panel_lifes(obj);
 				if (obj->type == PLAYER_JAKE) {
-					g_vars.screen_draw_offset ^= 0x2000;
-					screen_draw_number(obj->lifes_count - 1, 48, 163, 2);
-					g_vars.screen_draw_offset ^= 0x2000;
 					screen_draw_number(obj->lifes_count - 1, 48, 163, 2);
 				} else {
-					g_vars.screen_draw_offset ^= 0x2000;
-					screen_draw_number(obj->lifes_count - 1, 216, 163, 2);
-					g_vars.screen_draw_offset ^= 0x2000;
 					screen_draw_number(obj->lifes_count - 1, 216, 163, 2);
 				}
 			} else if (obj->type == PLAYER_JAKE) {
 				g_vars.player2_scrolling_flag = 1;
-				g_vars.screen_unk1 = 1;
+				g_vars.switch_player_scrolling_flag = 1;
 				obj39->special_anim = 16;
 				g_vars.player2_dead_flag = 1;
-				g_vars.screen_draw_offset ^= 0x2000;
-				screen_draw_frame(g_res.spr_frames[116], 12, 16, 8, 161);
-				g_vars.screen_draw_offset ^= 0x2000;
 				screen_draw_frame(g_res.spr_frames[116], 12, 16, 8, 161);
 			} else { // PLAYER_ELWOOD
 				g_vars.player2_scrolling_flag = 0;
-				g_vars.screen_unk1 = 1;
+				g_vars.switch_player_scrolling_flag = 1;
 				obj40->special_anim = 16;
 				g_vars.player1_dead_flag = 1;
-				g_vars.screen_draw_offset ^= 0x2000;
-				screen_draw_frame(g_res.spr_frames[118], 12, 16, 176, 161);
-				g_vars.screen_draw_offset ^= 0x2000;
 				screen_draw_frame(g_res.spr_frames[118], 12, 16, 176, 161);
 			}
 			if (g_vars.player2_dead_flag && g_vars.player1_dead_flag) {
@@ -1068,17 +1076,11 @@ static void do_level_update_panel_vinyls(struct object_t *obj) {
 	}
 	if (!g_vars.two_players_flag) {
 		if (obj->vinyls_count != g_vars.vinyls_count) {
-			g_vars.screen_draw_offset ^= 0x2000;
-			screen_draw_number(obj->vinyls_count, 192, 163, 2);
-			g_vars.screen_draw_offset ^= 0x2000;
 			screen_draw_number(obj->vinyls_count, 192, 163, 2);
 		}
 		g_vars.vinyls_count = obj->vinyls_count;
 	} else {
 		if (obj->vinyls_count != g_vars.vinyls_count) {
-			g_vars.screen_draw_offset ^= 0x2000;
-			screen_draw_number(obj->vinyls_count, 112, 163, 2);
-			g_vars.screen_draw_offset ^= 0x2000;
 			screen_draw_number(obj->vinyls_count, 112, 163, 2);
 		}
 		g_vars.vinyls_count = obj->vinyls_count;
@@ -1100,9 +1102,6 @@ static void do_level_update_panel_2nd_player() {
 		do_level_update_panel_lifes(obj);
 	}
 	if (obj->vinyls_count != g_vars.vinyls_count) {
-		g_vars.screen_draw_offset ^= 0x2000;
-		screen_draw_number(obj->vinyls_count, 280, 163, 2);
-		g_vars.screen_draw_offset ^= 0x2000;
 		screen_draw_number(obj->vinyls_count, 280, 163, 2);
 		g_vars.vinyls_count = obj->vinyls_count;
 	}
@@ -1196,7 +1195,6 @@ void do_level_enter_door(struct object_t *obj) {
 				do_level_update_panel_2nd_player();
 			}
 			screen_flip();
-			g_vars.screen_draw_offset ^= 0x2000;
 			do_level_redraw_tilemap(g_vars.screen_tilemap_xorigin, g_vars.screen_tilemap_yorigin);
 			do_level_update_scrolling2();
 			draw_level_panel();
@@ -1206,7 +1204,6 @@ void do_level_enter_door(struct object_t *obj) {
 			}
 			screen_do_transition1(1);
 			screen_flip();
-			g_vars.screen_draw_offset ^= 0x2000;
 			obj->unk3D = 0;
 			obj->sprite_type = 0;
 			obj->yacc = 2;
@@ -1334,7 +1331,7 @@ static void do_level_update_scrolling(struct object_t *obj) {
 		g_vars.screen_scrolling_dirmask = 0;
 		return;
 	}
-	if (g_vars.screen_unk1) {
+	if (g_vars.switch_player_scrolling_flag) {
 		if (obj->screen_xpos > (TILEMAP_SCREEN_W - 144)) {
 			g_vars.screen_scrolling_dirmask |= 2;
 		}
@@ -1343,26 +1340,26 @@ static void do_level_update_scrolling(struct object_t *obj) {
 		}
 		if ((g_vars.screen_scrolling_dirmask & 2) != 0 && obj->screen_xpos < TILEMAP_SCREEN_W / 2) {
 			g_vars.screen_scrolling_dirmask &= ~2;
-			g_vars.screen_unk1 = 0;
+			g_vars.switch_player_scrolling_flag = 0;
 			g_vars.inp_keyboard[0xC1] = 0;
 		}
 		if ((g_vars.screen_scrolling_dirmask & 1) != 0 && obj->screen_xpos > TILEMAP_SCREEN_W / 2) {
 			g_vars.screen_scrolling_dirmask &= ~1;
-			g_vars.screen_unk1 = 0;
+			g_vars.switch_player_scrolling_flag = 0;
 			g_vars.inp_keyboard[0xC1] = 0;
 		}
 	} else {
 		int _si = (obj->xvelocity >> 3) + obj->unk1C;
-		if (obj->screen_xpos > (TILEMAP_SCREEN_W - 64) && (g_vars.screen_tilemap_w * 16 - TILEMAP_SCREEN_W) > g_vars.screen_tilemap_xorigin) {
+		if (obj->screen_xpos > (TILEMAP_SCREEN_W - TILEMAP_SCROLL_W) && (g_vars.screen_tilemap_w * 16 - TILEMAP_SCREEN_W) > g_vars.screen_tilemap_xorigin) {
 			g_vars.screen_scrolling_dirmask |= 2;
 		}
-		if (obj->screen_xpos < 64 && g_vars.screen_tilemap_xorigin > 0) {
+		if (obj->screen_xpos < TILEMAP_SCROLL_W && g_vars.screen_tilemap_xorigin > 0) {
 			g_vars.screen_scrolling_dirmask |= 1;
 		}
-		if ((g_vars.screen_scrolling_dirmask & 2) != 0 && (obj->screen_xpos < 48 || _si <= 0)) {
+		if ((g_vars.screen_scrolling_dirmask & 2) != 0 && (obj->screen_xpos < (TILEMAP_SCROLL_W - 16) || _si <= 0)) {
 			g_vars.screen_scrolling_dirmask &= ~2;
 		}
-		if ((g_vars.screen_scrolling_dirmask & 1) != 0 && (obj->screen_xpos > (TILEMAP_SCREEN_W - 48) || _si >= 0)) {
+		if ((g_vars.screen_scrolling_dirmask & 1) != 0 && (obj->screen_xpos > (TILEMAP_SCREEN_W - (TILEMAP_SCROLL_W - 16)) || _si >= 0)) {
 			g_vars.screen_scrolling_dirmask &= ~1;
 		}
 	}
@@ -1392,7 +1389,7 @@ static void do_level_update_object_bounds(struct object_t *obj) {
 			tmp_dx = GAME_SCREEN_W;
 			tmp_dy = GAME_SCREEN_H;
 		}
-		if (ABS(_si) >= ABS(tmp_dx) && ABS(_di) >= ABS(tmp_dy)) {
+		if (abs(_si) >= abs(tmp_dx) && abs(_di) >= abs(tmp_dy)) {
 			obj->player_xdist = tmp_dx;
 			obj->player_ydist = tmp_dy;
 			// obj->unk41 = 1;
@@ -1917,13 +1914,13 @@ static void do_level_update_objects() {
 		obj->direction_ud = 0;
 		if (obj->type < 2) {
 			if (g_vars.inp_keyboard[0xC1] != 0) { // F7, change player
-				if (!g_vars.screen_unk1 && g_vars.two_players_flag) {
+				if (!g_vars.switch_player_scrolling_flag && g_vars.two_players_flag) {
 					if (!g_vars.player2_scrolling_flag && g_vars.objects[OBJECT_NUM_PLAYER1].unk53 == 0) {
 						g_vars.player2_scrolling_flag = 1;
-						g_vars.screen_unk1 = 1;
+						g_vars.switch_player_scrolling_flag = 1;
 					} else if (g_vars.player2_scrolling_flag && g_vars.objects[OBJECT_NUM_PLAYER2].unk53 == 0) {
 						g_vars.player2_scrolling_flag = 1;
-						g_vars.screen_unk1 = 1;
+						g_vars.switch_player_scrolling_flag = 1;
 					}
 				}
 				g_vars.inp_keyboard[0xC1] = 0;
@@ -2026,15 +2023,9 @@ static void do_level_update_objects() {
 	if (g_vars.triggers_counter != 0) {
 		if (g_vars.triggers_counter < 10) {
 			screen_draw_frame(g_res.spr_frames[140 + g_vars.level], 12, 16, g_vars.level * 32 + 80, -12);
-			g_vars.screen_draw_offset = 0x2000;
-			screen_draw_frame(g_res.spr_frames[140 + g_vars.level], 12, 16, g_vars.level * 32 + 80, -12);
-			g_vars.screen_draw_offset ^= 0x2000;
 			++g_vars.triggers_counter;
 		} else {
 			screen_draw_frame(g_res.spr_frames[145], 12, 16, g_vars.level * 32 + 80, -12);
-			g_vars.screen_draw_offset = 0x2000;
-			screen_draw_frame(g_res.spr_frames[145], 12, 16, g_vars.level * 32 + 80, -12);
-			g_vars.screen_draw_offset ^= 0x2000;
 			++g_vars.triggers_counter;
 			if (g_vars.triggers_counter > 20) {
 				g_vars.triggers_counter = 1;
@@ -2070,18 +2061,15 @@ static void do_level_update_objects() {
 			g_vars.objects[OBJECT_NUM_PLAYER2].data5F = 0;
 			g_vars.objects[OBJECT_NUM_PLAYER1].flag_end_level = 0;
 			g_vars.objects[OBJECT_NUM_PLAYER2].flag_end_level = 0;
-			g_vars.screen_draw_offset -= TILEMAP_OFFSET_Y * 40;
+			// g_vars.screen_draw_offset -= TILEMAP_OFFSET_Y * 40;
 			screen_unk5();
-			g_vars.screen_draw_offset += TILEMAP_OFFSET_Y * 40;
+			// g_vars.screen_draw_offset += TILEMAP_OFFSET_Y * 40;
 			g_vars.quit_level_flag = 1;
 		}
 	} else if (g_vars.game_over_flag) {
 		g_vars.screen_scrolling_dirmask = 0;
 		if ((!g_vars.two_players_flag && g_vars.objects[OBJECT_NUM_PLAYER1].lifes_count == 1) || (g_vars.player2_dead_flag && g_vars.player1_dead_flag)) {
 			screen_draw_frame(g_res.spr_frames[127], 34, 160, 80, 63);
-			g_vars.screen_draw_offset ^= 0x2000;
-			screen_draw_frame(g_res.spr_frames[127], 34, 160, 80, 63);
-			g_vars.screen_draw_offset ^= 0x2000;
 			g_vars.objects[OBJECT_NUM_PLAYER1].unk60 = 0;
 			g_vars.objects[OBJECT_NUM_PLAYER2].unk60 = 0;
 			g_vars.objects[OBJECT_NUM_PLAYER1].data5F = 0;
@@ -2106,9 +2094,9 @@ static void do_level_update_objects() {
 			if (!g_vars.two_players_flag && g_vars.objects[OBJECT_NUM_PLAYER1].lifes_count == 1) {
 				g_vars.play_level_flag = 0;
 			}
-			g_vars.screen_draw_offset -= TILEMAP_OFFSET_Y * 40;
+			// g_vars.screen_draw_offset -= TILEMAP_OFFSET_Y * 40;
 			screen_unk5();
-			g_vars.screen_draw_offset += TILEMAP_OFFSET_Y * 40;
+			// g_vars.screen_draw_offset += TILEMAP_OFFSET_Y * 40;
 			g_vars.quit_level_flag = 1;
 		}
 	}
@@ -2128,8 +2116,8 @@ static void draw_foreground_tiles() {
 			}
 			const int avt_num = g_res.triggers[num].foreground_tile_num;
 			if (avt_num != 255) {
-				const int tile_y = j * 16 + TILEMAP_OFFSET_Y;
-				const int tile_x = i * 16;
+				const int tile_y = g_vars.screen_tilemap_yoffset + j * 16 + TILEMAP_OFFSET_Y;
+				const int tile_x = g_vars.screen_tilemap_xoffset + i * 16;
 				render_add_sprite(RENDER_SPR_FG, avt_num, tile_x, tile_y, 0);
 			}
 		}
@@ -2144,12 +2132,10 @@ void do_level() {
 	}
 	g_vars.screen_tilemap_w = level_dim[g_vars.level * 2];
 	g_vars.screen_tilemap_h = level_dim[g_vars.level * 2 + 1];
-	g_vars.screen_tilemap_w16 = g_vars.screen_tilemap_w;
-	g_vars.screen_tilemap_h16 = g_vars.screen_tilemap_h >> 4;
 	for (int i = 0; i < MAX_TRIGGERS; ++i) {
 		g_res.triggers[i].unk16 = i;
 	}
-	g_vars.screen_unk1 = 0;
+	g_vars.switch_player_scrolling_flag = 0;
 	init_level();
 	screen_clear(0);
 	do_level_redraw_tilemap(g_vars.screen_tilemap_xorigin, g_vars.screen_tilemap_yorigin);
@@ -2160,7 +2146,7 @@ void do_level() {
 		g_sys.set_palette_amiga(_colors_data + g_vars.level * 16, 0);
 	}
 	g_vars.inp_keyboard[0xB9] = 0; // SPACE
-	g_vars.screen_draw_offset = TILEMAP_OFFSET_Y * 40;
+	// g_vars.screen_draw_offset = TILEMAP_OFFSET_Y * 40;
 	g_vars.update_objects_counter = 0;
 	g_vars.game_over_flag = 0;
 	g_vars.level_completed_flag = 0;
@@ -2169,6 +2155,7 @@ void do_level() {
 	g_vars.screen_draw_h = TILEMAP_SCREEN_H;
 	g_vars.found_music_instrument_flag = 0;
 	render_set_sprites_clipping_rect(0, TILEMAP_OFFSET_Y, TILEMAP_SCREEN_W, TILEMAP_SCREEN_H);
+	bool screen_transition_flag = true;
 	do {
 		const uint32_t timestamp = g_sys.get_timestamp();
 		update_input();
@@ -2192,24 +2179,32 @@ void do_level() {
 		// demo
 		do_level_update_scrolling2();
 		do_level_update_objects();
-		screen_clear_last_sprite();
 		screen_redraw_sprites();
-		if (!g_options.amiga_data) {
+		if (!g_res.amiga_data) {
 			draw_foreground_tiles();
 		}
 		++g_vars.level_loop_counter;
 		draw_level_panel();
-		screen_unk6();
+
+		if (screen_transition_flag) {
+			screen_transition_flag = false;
+			g_sys.update_screen(g_res.vga, 0);
+			screen_do_transition2();
+		} else {
+			g_sys.update_screen(g_res.vga, 1);
+		}
+		memset(g_res.vga, 0, GAME_SCREEN_W * GAME_SCREEN_H);
 
 		const int diff = (timestamp + (1000 / 30)) - g_sys.get_timestamp();
 		g_sys.sleep(diff < 10 ? 10 : diff);
 		screen_clear_sprites();
 
 	} while (!g_sys.input.quit && !g_vars.quit_level_flag);
-	g_vars.screen_draw_offset -= TILEMAP_OFFSET_Y * 40;
+	// g_vars.screen_draw_offset -= TILEMAP_OFFSET_Y * 40;
 	screen_unk5();
 	if (g_options.amiga_copper_bars) {
 		g_sys.set_copper_bars(0);
 	}
+	render_set_sprites_clipping_rect(0, 0, GAME_SCREEN_W, GAME_SCREEN_H);
 	g_vars.inp_keyboard[0xBF] = 0;
 }
diff --git a/main.c b/main.c
index d61f48a..6bc67b6 100644
--- a/main.c
+++ b/main.c
@@ -35,8 +35,8 @@ int main(int argc, char *argv[]) {
 	g_options.screen_h = 200;
 	g_options.amiga_copper_bars =  true;
 	g_options.amiga_colors = true;
-	// g_options.amiga_data = true;
 	// g_options.amiga_status_bar = true;
+	g_options.dos_scrolling = false;
 	const char *data_path = DEFAULT_DATA_PATH;
 	int scale_factor = DEFAULT_SCALE_FACTOR;
 	const char *scale_filter = DEFAULT_SCALE_FILTER;
@@ -91,10 +91,11 @@ int main(int argc, char *argv[]) {
 			scale_filter = strdup(optarg);
 			break;
 		case 9:
-			sscanf(optarg, "%dx%d", &g_options.screen_w, &g_options.screen_h);
-			// align to tile 16x16
-			g_options.screen_w =  (g_options.screen_w + 15) & ~15;
-			g_options.screen_h = ((g_options.screen_h + 15) & ~15) + 40;
+			if (sscanf(optarg, "%dx%d", &g_options.screen_w, &g_options.screen_h) == 2) {
+				// align to tile 16x16
+				g_options.screen_w =  (g_options.screen_w + 15) & ~15;
+				g_options.screen_h = ((g_options.screen_h + 15) & ~15) + 40;
+			}
 			break;
 		default:
 			fprintf(stdout, USAGE, argv[0]);
diff --git a/resource.c b/resource.c
index b0af510..1f78b83 100644
--- a/resource.c
+++ b/resource.c
@@ -48,7 +48,10 @@ void res_init(int vga_size) {
 		}
 	}
 	if (fio_exists("demomag.sql")) {
-		g_res.flags = RESOURCE_FLAGS_DEMO;
+		g_res.dos_demo = true;
+	}
+	if (fio_exists("mag.tbl")) {
+		g_res.amiga_data = true;
 	}
 }
 
diff --git a/resource.h b/resource.h
index c94b2e2..b8616bc 100644
--- a/resource.h
+++ b/resource.h
@@ -28,10 +28,7 @@ struct trigger_t {
 #define SOUND_SIZE     29376
 #define SPRITES_COUNT    146
 
-#define RESOURCE_FLAGS_DEMO (1 << 0)
-
 struct resource_data_t {
-	uint32_t flags;
 	uint8_t *sql;
 	uint8_t *spr_sqv;
 	uint8_t *avt_sqv;
@@ -46,6 +43,8 @@ struct resource_data_t {
 	int vga_size;
 	uint8_t *tiles;
 	uint8_t *snd;
+	bool dos_demo;
+	bool amiga_data;
 };
 
 extern struct resource_data_t g_res;
diff --git a/screen.c b/screen.c
index 8a1d48e..b02ca70 100644
--- a/screen.c
+++ b/screen.c
@@ -41,9 +41,6 @@ void screen_add_sprite(int x, int y, int frame) {
 	add_game_sprite(x, y, frame, 0);
 }
 
-void screen_clear_last_sprite() {
-}
-
 void screen_redraw_sprites() {
 }
 
@@ -70,7 +67,7 @@ void screen_draw_frame(const uint8_t *frame, int fh, int fw, int x, int y) {
 		y += _offset_y;
 	}
 	y += fh + 2;
-	if (g_options.amiga_status_bar) {
+	if (g_options.amiga_status_bar || g_res.amiga_data) {
 		if (frame == g_res.spr_frames[123] || frame == g_res.spr_frames[124]) { // top or bottom status bar
 			for (int x = 0; x < GAME_SCREEN_W; x += 16) {
 				decode_amiga_gfx(g_res.vga + y * GAME_SCREEN_W + x, GAME_SCREEN_W, 16, 12, 4, frame, 16, 0x20, 0xFFFF);
@@ -91,64 +88,64 @@ void screen_flip() {
 	g_sys.update_screen(g_res.vga, 1);
 }
 
-void screen_unk4() {
+void screen_copy_img() {
 	memcpy(g_res.vga, g_res.tmp + 32000, GAME_SCREEN_W * GAME_SCREEN_H);
 }
 
 void screen_unk5() {
-	screen_clear(0);
-	screen_do_transition2();
-	screen_clear(0);
-}
-
-void screen_unk6() {
-	// g_vars.screen_draw_offset -= 12;
 	// screen_do_transition2();
-	// g_vars.screen_draw_offset += 12;
-	g_sys.update_screen(g_res.vga, 1);
-	memset(g_res.vga, 0, GAME_SCREEN_W * GAME_SCREEN_H);
-}
-
-static void screen_unk13(int a) {
+	screen_clear(0);
 }
 
 void screen_do_transition1(int a) {
-	int i, count, increment;
-	if (a != 0) {
-		i = 11;
-		count = 0;
-		increment = -1;
-	} else {
-		screen_clear(0);
-		i = 0;
-		count = 11;
-		increment = 1;
-	}
-	while (i != count) {
-		screen_unk13(i);
-		screen_unk13(19 - i);
-		screen_vsync();
-		i += increment;
+	print_warning("screen_do_transition1 %d", a);
+	if (a) {
+		g_sys.transition_screen(TRANSITION_CURTAIN, true);
 	}
 }
 
 void screen_do_transition2() {
 	print_warning("screen_do_transition2");
+	g_sys.transition_screen(TRANSITION_SQUARE, true);
 }
 
 void screen_clear(int a) {
 	memset(g_res.vga, 0, GAME_SCREEN_W * GAME_SCREEN_H);
 }
 
-void screen_draw_tile(int tile, int dst, int type) {
-	const int y = (dst / 640) * 16 + TILEMAP_OFFSET_Y;
-	const int x = (dst % 640) / 2 * 16;
+void screen_draw_tile(int tile, int type, int x, int y) {
 	const uint8_t *src = g_res.tiles + tile * 16;
 	if (type == 4) {
 		src += 320;
 	}
-	for (int i = 0; i < 16; ++i) {
-		memcpy(g_res.vga + (y + i) * GAME_SCREEN_W + x, src, 16);
+	x = g_vars.screen_tilemap_xoffset + x * 16;
+	int tile_w = 16;
+	if (x < 0) {
+		tile_w += x;
+		src -= x;
+		x = 0;
+	}
+	if (x + tile_w > TILEMAP_SCREEN_W) {
+		tile_w = TILEMAP_SCREEN_W - x;
+	}
+	if (tile_w <= 0) {
+		return;
+	}
+	y = g_vars.screen_tilemap_yoffset + y * 16;
+	int tile_h = 16;
+	if (y < 0) {
+		tile_h += y;
+		src -= y * 640;
+		y = 0;
+	}
+	if (y + tile_h > TILEMAP_SCREEN_H) {
+		tile_h = TILEMAP_SCREEN_H - y;
+	}
+	if (tile_h <= 0) {
+		return;
+	}
+	for (int i = 0; i < tile_h; ++i) {
+		memcpy(g_res.vga + (TILEMAP_OFFSET_Y + y + i) * GAME_SCREEN_W + x, src, tile_w);
 		src += 640;
 	}
 }
@@ -174,7 +171,7 @@ void screen_draw_number(int num, int x, int y, int color) {
 		y += _offset_y;
 	}
 	y += TILEMAP_OFFSET_Y;
-	if (g_options.amiga_status_bar) {
+	if (g_options.amiga_status_bar || g_res.amiga_data) {
 		draw_number_amiga(num / 10, x - 8, y - 2);
 		draw_number_amiga(num % 10, x,     y - 2);
 	} else {
@@ -204,7 +201,7 @@ static void decode_graphics(int spr_type, int start, int end) {
 	struct sys_rect_t r[MAX_SPR_FRAMES];
 	uint8_t *data = (uint8_t *)calloc(MAX_SPRITESHEET_W * MAX_SPRITESHEET_H, 1);
 	if (data) {
-		const int depth = g_options.amiga_data && (start == 0) ? 3 : 4;
+		const int depth = g_res.amiga_data && (start == 0) ? 3 : 4;
 		int current_x = 0;
 		int max_w = 0;
 		int current_y = 0;
@@ -230,7 +227,7 @@ static void decode_graphics(int spr_type, int start, int end) {
 					max_h = h;
 				}
 			}
-			decode_spr(ptr, w, w, h, depth, data, MAX_SPRITESHEET_W, current_x, current_y, g_options.amiga_data);
+			decode_spr(ptr, w, w, h, depth, data, MAX_SPRITESHEET_W, current_x, current_y, g_res.amiga_data);
 			r[j].x = current_x;
 			r[j].y = current_y;
 			r[j].w = w;
@@ -243,7 +240,7 @@ static void decode_graphics(int spr_type, int start, int end) {
 		assert(max_w <= MAX_SPRITESHEET_W);
 		assert(current_y + max_h <= MAX_SPRITESHEET_H);
 		render_unload_sprites(spr_type);
-		const int palette_offset = (g_options.amiga_data && start == 0) ? 16 : 0;
+		const int palette_offset = (g_res.amiga_data && start == 0) ? 16 : 0;
 		render_load_sprites(spr_type, end - start, r, data, MAX_SPRITESHEET_W, current_y + max_h, palette_offset);
 		free(data);
 	}
@@ -273,7 +270,7 @@ void screen_load_graphics() {
 			free(data);
 		}
 		// background tiles (Amiga) - re-arrange to match DOS .ck1/.ck2 layout
-		if (g_options.amiga_data) {
+		if (g_res.amiga_data) {
 			static const int BG_TILES_COUNT = 256;
 			static const int W = 320 / 16;
 			memcpy(g_res.tmp, g_res.tiles, BG_TILES_COUNT * 16 * 8);
diff --git a/sys.h b/sys.h
index fb3745a..b1b1722 100644
--- a/sys.h
+++ b/sys.h
@@ -25,6 +25,11 @@ struct sys_rect_t {
 	int w, h;
 };
 
+enum sys_transition_e {
+	TRANSITION_SQUARE,
+	TRANSITION_CURTAIN
+};
+
 struct sys_t {
 	struct input_t	input;
 	int	(*init)();
@@ -36,6 +41,7 @@ struct sys_t {
 	void	(*fade_in_palette)();
 	void	(*fade_out_palette)();
 	void	(*update_screen)(const uint8_t *p, int present);
+	void	(*transition_screen)(enum sys_transition_e type, bool open);
 	void	(*process_events)();
 	void	(*sleep)(int duration);
 	uint32_t	(*get_timestamp)();
diff --git a/sys_sdl2.c b/sys_sdl2.c
index 9db7a0a..dd24de8 100644
--- a/sys_sdl2.c
+++ b/sys_sdl2.c
@@ -192,6 +192,40 @@ static void sdl2_fade_out_palette() {
 	fade_palette_helper(0);
 }
 
+static void sdl2_transition_screen(enum sys_transition_e type, bool open) {
+	const int step_w = _screen_w / FADE_STEPS;
+	const int step_h = _screen_h / FADE_STEPS;
+	SDL_Rect r;
+	r.x = 0;
+	r.w = 0;
+	r.y = 0;
+	r.h = (type == TRANSITION_CURTAIN) ? _screen_h : 0;
+	do {
+		r.x = (_screen_w - r.w) / 2;
+		if (r.x < 0) {
+			r.x = 0;
+		}
+		r.w += step_w;
+		if (r.x + r.w > _screen_w) {
+			r.w = _screen_w - r.x;
+		}
+		if (type == TRANSITION_SQUARE) {
+			r.y = (_screen_h - r.h) / 2;
+			if (r.y < 0) {
+				r.y = 0;
+			}
+			r.h += step_h;
+			if (r.y + r.h > _screen_h) {
+				r.h = _screen_h - r.y;
+			}
+		}
+		SDL_RenderClear(_renderer);
+		SDL_RenderCopy(_renderer, _texture, &r, &r);
+		SDL_RenderPresent(_renderer);
+		SDL_Delay(30);
+	} while (r.x > 0 && (type == TRANSITION_CURTAIN || r.y > 0));
+}
+
 static void sdl2_update_screen(const uint8_t *p, int present) {
 	if (_copper_color != -1) {
 		for (int j = 0; j < _screen_h; ++j) {
@@ -459,6 +493,7 @@ struct sys_t g_sys = {
 	.fade_in_palette	= sdl2_fade_in_palette,
 	.fade_out_palette	= sdl2_fade_out_palette,
 	.update_screen	= sdl2_update_screen,
+	.transition_screen = sdl2_transition_screen,
 	.process_events	= sdl2_process_events,
 	.sleep	= sdl2_sleep,
 	.get_timestamp = sdl2_get_timestamp,
diff --git a/triggers.c b/triggers.c
index fa10362..6ccd99f 100644
--- a/triggers.c
+++ b/triggers.c
@@ -79,7 +79,7 @@ static void trigger_func_op2(struct object_t *obj) {
 		obj->ypos16 = obj->ypos >> 4;
 		obj->sprite_type = 1;
 		obj->yfriction = 0;
-		if (!g_vars.screen_unk1) {
+		if (!g_vars.switch_player_scrolling_flag) {
 			obj->unk1C = 5;
 		}
 	} else if (obj->yvelocity < 0) {
@@ -90,7 +90,7 @@ static void trigger_func_op2(struct object_t *obj) {
 		obj->yfriction = 0;
 	}
 	obj->unk2F = 0;
-	if (g_vars.screen_unk1) {
+	if (g_vars.switch_player_scrolling_flag) {
 		obj->special_anim = 18;
 		obj->anim_num = 1;
 	}
@@ -114,7 +114,7 @@ static void trigger_func_op3(struct object_t *obj) {
 		obj->ypos = obj->ypos16 << 4;
 		obj->screen_xpos = obj->xpos - g_vars.screen_tilemap_xorigin;
 		obj->screen_ypos = obj->ypos - g_vars.screen_tilemap_yorigin;
-		g_vars.screen_unk1 = 1;
+		g_vars.switch_player_scrolling_flag = 1;
 	}
 }
 
@@ -825,9 +825,6 @@ void triggers_update_tiles1(struct object_t *obj) {
 					g_vars.objects[OBJECT_NUM_PLAYER2].data5F = p[7];
 				}
 				screen_draw_frame(g_res.spr_frames[140 + g_vars.level], 12, 16, 80 + g_vars.level * 32, -12);
-				g_vars.screen_draw_offset ^= 0x2000;
-				screen_draw_frame(g_res.spr_frames[140 + g_vars.level], 12, 16, 80 + g_vars.level * 32, -12);
-				g_vars.screen_draw_offset ^= 0x2000;
 				g_vars.found_music_instrument_flag = 1;
 				g_vars.triggers_counter = 0;
 				play_sound(SOUND_12);
@@ -883,19 +880,10 @@ void triggers_update_tiles1(struct object_t *obj) {
 			++obj->lifes_count;
 			if (!g_vars.two_players_flag) {
 				screen_draw_number(obj->lifes_count - 1, 64, 163, 2);
-				g_vars.screen_draw_offset ^= 0x2000;
-				screen_draw_number(obj->lifes_count - 1, 64, 163, 2);
-				g_vars.screen_draw_offset ^= 0x2000;
-			} else if (obj->type == 0) {
+			} else if (obj->type == PLAYER_JAKE) {
 				screen_draw_number(obj->lifes_count - 1, 48, 163, 2);
-				g_vars.screen_draw_offset ^= 0x2000;
-				screen_draw_number(obj->lifes_count - 1, 48, 163, 2);
-				g_vars.screen_draw_offset ^= 0x2000;
 			} else {
 				screen_draw_number(obj->lifes_count - 1, 216, 163, 2);
-				g_vars.screen_draw_offset ^= 0x2000;
-				screen_draw_number(obj->lifes_count - 1, 216, 163, 2);
-				g_vars.screen_draw_offset ^= 0x2000;
 			}
 		}
 	} else {
@@ -931,7 +919,7 @@ void triggers_update_tiles2(struct object_t *obj) {
 		obj->anim_num = 1;
 		obj->unk2F = 0;
 		obj->xvelocity = p[3] - 100;
-		obj->xmaxvelocity = ABS(obj->xvelocity);
+		obj->xmaxvelocity = abs(obj->xvelocity);
 		do_level_player_hit(obj);
 	}
 	obj->trigger3_num = 0;