Literally anything will do.
Blocks, characters, bows, arrows, new modes, new options, pcvr, bugfixes, music, replays, a rank system that lets you rank up when winning and rank down when losing, recover from the smallest network problem without dropping from a match, performance fix that makes 3v3 playable (maybe the game doesn't need as many triangles. Maybe the game doesn't need as many mirrors), the magic technology that lets 5ghz wifi be usable for this game...
Just please take whatever you are working on and release it