Needs some work
Game feels a bit unfinished, the mechanics are fun, like the way you get upgrades.
After a while of playing, a lot of mobs spawn, and with gems popping out of them like crazy, the game slows down heavily (and I have a decent machine)
I also got annoyed that gems would disappear if more than x gems were on the screen, with the number of mobs in my way, I hardly was able to pick anything up because as I was getting closer to some gems to pick them up and blasting mobs on the way, new gems would pop out and fly away from me, and the ones I was after disappear. I know you can use the magnet to get gems to come to you, but even then, before they come to me, they disappear from the massive amounts of gems flying all over the place.
Also, it took me a while to understand the point of the game, at first I thought I was suppose to complete the level somehow. Only later did I figure out it was sort of a never ending thing.
I think you this game would be more fun if it was made into more of a side scroller with levels you need to complete, using the same mechanics developed here, as I liked how you get upgrades.