Added the changes I proposed a while back.

So now, when currentGame.gamePlay is set to GAMEPLAY_ONPON:
- You start with 50 shield, and never gain any increased capacity.
- You can't charge the charge cannon and shoot at the same time; if
  you shoot the plasma gun, the charge cannon shoots as well (as if
  you had released the charge key).

I didn't add in the feature to keep the view from slowing you down,
because the method I used was imperfect anyway.

src/game.cpp

@@ -70,10 +70,19 @@ void newGame()
 	currentGame.maxPlasmaAmmo = 100;
 	currentGame.maxRocketAmmo = 10;
 
+    if (currentGame.gamePlay == GAMEPLAY_ONPON)
+    {
+        currentGame.shieldUnits = 2;
+        player.maxShield = 50;
+        player.shield = 50;
+    }
+    else
+    {
 	    currentGame.shieldUnits = 1;
-
 	    player.maxShield = 25;
 	    player.shield = 25;
+	}
+
 	player.ammo[0] = 0;
 	player.ammo[1] = 5;
 	player.weaponType[0] = W_PLAYER_WEAPON;

src/missions.cpp

@@ -160,6 +160,7 @@ void updateSystemStatus()
 		strcpy(currentGame.stationedName, "Nerod");
 		initPlanetMissions(currentGame.system);
 
+		if (currentGame.gamePlay != GAMEPLAY_ONPON)
 		    currentGame.shieldUnits = 2;
 	}
 	else if (currentGame.area == 11)
@@ -170,6 +171,7 @@ void updateSystemStatus()
 		strcpy(currentGame.stationedName, "Odeon");
 		initPlanetMissions(currentGame.system);
 
+		if (currentGame.gamePlay != GAMEPLAY_ONPON)
 		    currentGame.shieldUnits = 3;
 	}
 	else if (currentGame.area == 18)
@@ -180,6 +182,7 @@ void updateSystemStatus()
 		strcpy(currentGame.stationedName, "Pluto");
 		initPlanetMissions(currentGame.system);
 
+		if (currentGame.gamePlay != GAMEPLAY_ONPON)
 		    currentGame.shieldUnits = 4;
 	}
 	else // Update the mission for the planet

src/player.cpp

@@ -113,7 +113,7 @@ void doPlayer()
 
 			if (player.weaponType[1] == W_CHARGER)
 			{
-				if (engine.keyState[SDLK_SPACE])
+				if (engine.keyState[SDLK_SPACE] && !(currentGame.gamePlay == GAMEPLAY_ONPON && (engine.keyState[SDLK_LCTRL] || engine.keyState[SDLK_RCTRL])))
 				{
 					limitCharAdd(&player.ammo[1], 1, 0, 200);
 				}