Really enjoyed it I especially liked the roaming opponent that would fire 2 missles then reload, and the spoked opponent that expands and contracts. The powerups were also very fun (sentry gun+homing missiles FTW!)

One thing I would change is the homing "+" enemy. When you die, I think these guys should lose lock and wander away. As it stands, they hover over your spawn point and make it tough to fight back when you respawn.

Maybe the easiest solution is to make your respawn a different random spot than where you died. Or maybe a random empty spot so you don't come back right inside a new enemy. [Generate random points inside of a while loop, do proximity queries from that point, and kick out of the loop once a reasonably empty spot is found?] You could add some audio/visual cues when the respawns so the randomization won't be as disorienting.