The levels with the filth monsters were quite hard but I still did them first try! The load game text entry works fine for me.

For the impulse function, I guess you can find the normal velocity component and apply that to the object's linear velocity. But for the tangential component, I am not sure how to calculate how much of it will go into rotation and how much will go into translation.

Maybe you could combine left/right handed controls, for example this for the up key: if(Greenfoot.isKeyDown("w") || Greenfoot.isKeyDown("up")) { //Do Something }