best: 735. will be back for this one, bet i could get really far. what a great set of mechanics. seriously. kudos on several design decisions, plays great!
my trick is to let the ones on the far left side stay and I just keep moving. hide behind whatever spawns in the middle (to let the left ones do the killing for you) and shoot anything that spawns on the right.
edit- oh yeah: music choice was great. i don't know how to do it in unity *shrug* but this game would really jam if the bad guys shot on the beat of the music