Good idea, and nice execution! some feedback:
- The controls felt wrong. I feel like gamepad or mouse-based controls would make the game more fun.
- It was difficult for me to remember what each side did. Like sure, green and snow are self evident, but then yellow, red, blue. I forget immediately!
- The timer-based wave-based gameplay felt a bit wrong. I'd suggest having a timer + spawning balls based on how many are left on screen, to avoid dead time
Don't get all that criticism let you think I didn't like the game. I thought it was very nice, and did a lot with very little.