Pretty cool!
I think it would help if the shards were a different colour - at least for me it took a long time to realise in the first level that I was supposed to collect that (it just kinda looked like another part of the map).
And I was sad when I got hit by the enemy and then had to start from the beginning again (no 'checkpoint') - but I guess you ran you ran out of time for that. The upgrade system is pretty nifty and the game mechanics were well implemented!
Keep it up!