Okay, played a bit more. Yeah, the UI now works. Overall I think the game is kinda easy, because all I was doing is aimlessly jumping around as hopping bunnies were demolishing everything on screen to the point I wasn't sure where the enemies are.
Additionally there's that timer, and I don't really understand if I'm just supposed to survive as many waves as possible or what before it runs out. The game doesn't really explain that.