Glad to see that with the workaround it works! For the difficulty settings it uses a different code, my bad, just uploaded a version with that fixed (still needs to press F1 first) Difficulty selection does not use a mouse at all, so if it is glitching there it means something is being considered as a controller and messing things up (maybe even the mousepad?¿). Long time ago the engine would detect a printer as a controller and we were very confused by it.
Regarding WASD that's already a feature, not super intuitive, but pressing ENTER loads a player that uses arrows (enter & backspace) and pressing SPACEBAR loads a player that uses WASD (spacebar & esc). We did it this way so two players could play on the same keyboard.