Things I'd do if I had more than 6 minutes left of the the 3-hour jam:
- Sort the sprites so you can't see them clipping into each other and the player
- Have a player sprite
- Make the prisms bounce up and down
- Have a pick-up sound
- Have more levels
- More colours - 3 just about does it to provide some interest, but I'd love to make it so that you "unlock" new colours as you pick up prisms/complete levels.
Things I would not do:
- Backgrounds - anything but pure black would it not work with the "you only see one colour" mechanic