Of course, you can contribute to one of the WIP projects on the bitbox wiki page (https://github.com/makapuf/bitbox/wiki/Software-Index) - frankly, many of those games need attention and could use some polish.
But hat if you can to create a simple project in a weekend (of course it will run on the bitbox, where else ?), here are some ideas of simple games to try !
- tron (which is a multiplayer snake)
- connect four
- flood it
- katamari damaci (!)
- grid lock
- missile command
- scortched earth
- dr mario
- diner dash
doodle jump(jumper :) https://github.com/makapuf/bitbox-jump )
- 2048 !
And here is someone who coded 50 games last year ! Can you do better ? (I don't :) )