So this engine is very difficult to break into, because it cannot render inside-out blocks, since it really doesn't need to, considering the game file already handles not seeing behind walls. The solution gets more complicated, you'd have to replace each RAYCAST X,Y occurrence with MAX(0,MIN(X,MAPWIDTH%-1)),MAX(0,MIN(Y,MAPHEIGHT%-1)) Soon enough you will have completely rebuilt the raycast engine.