>>11848660Changing the scroll position is a piece of cake, it's a single byte change. Look up in the RAM the X position of the turtle, the value will stop changing when the screen scrolls, set a break point to it and you should find the code that basically says "initiate scrolling when X position is this number" and you can change that number. You need to do it for going towards the right and the left.
The problem however in the case of TMNT is that, when you switch screen with a ladder, the scrolling position does not get reset, and coupled with the fact the enemies spawn position does not adapt to the scrolling position, mean that if you change the scrolling point enemies when entering a screen through a ladder will have their spawn positions altered. I fixed that by manually changing the problematic cases, but that's a shitty bandaid, the real fix would be to make sure all the spawns adapt to the position of the screen. However I opted for the bandaid because I wanted to change the placement of a few enemies which even in the base game spawn way too close to the player sometimes resulting in unavoidable hits.
Next glitch: in the rooftop level where you have to use the rope and retrieve an item crucial to progressing in the game, said item will not spawn if you use the rope while the screen is scrolled too far up ahead (due to the rope "artificially" scrolling the screen and said scrolling code not going through the normal item spawn routine). I haven't fixed this one, I just knew about it so I'd walk back & forth to make the item spawn.
[cont]