Yo! I've got a tiny request for the game.
Let us speed up the game with the right mouse button too (alongside Space Bar ofc).
It'd help for one-handed gameplay.
Edit: And a more ambitious idea; a "Custom Nights" type of level, where you basically choose the enemies that'll come at you, their difficulty, their spawn rate, etc etc. Could possibly even change the length of the level.
Completing a custom level would grant you the appropriate gems, but if you lose then you'd earn nothing.