Very cool game. It lacks a little in the sound design, but thats completely fine for a jam entry.
I find it awesome that it seems to be bug free - even when enemies spawn on top of the pillars they can be shot down - which is what I would expect to be an unpolished thing.
I got pretty far I think - it got a little overwhelming and I died, but I had a good time.
If completing a wave also gave you a checkpoint I might have even gone around finishing it.
Cool enemy varienty and all. Good job.