Hey Valsi!
Sorry I took so long to answer. Its been a hectic week:
1) You can use any open source tools or assets
2) Any engine you choose is permissible. Even one you've built yourself. What's important is that its clearly an 'engine' and not a 'prototype'  or unfinished game.
3) Under this theme all genres are permissible..  Only limitation on content would be no offensive content.

Hey. Glad you remember the game. You can remap keys now. Feel free to give the demo a try and see if it works for you! Currently working on the steam release atm.

Awesome! Will take a look.

Glad to hear you liked it!

Sorry to hear you had problems!

If possible kindly fill out the form here so I can pin point the issue.