First off, the graphics are excellent! The idea of your own bullets becoming hazards was not immediately communicated, but once understood, the gameplay became fast and strategic. The inclusion of several weapon types leads to a fair bit of replayability as well.
My biggest complaint is there didn't seem to be any sound effects whatsoever? Sound is just as important as visual feedback especially in fast-paced games, and even the inclusion of simple sounds will make all the difference.
Regardless, excellent work!