At it's core, it's Asteroids Meets Robotron with Weapon/Ship/Armor/Shield/Ally mods and upgrades. Wave based with bosses at certain set levels (lvl 40, 80, 100 always same 3 bosses - so far). Good variety of the Archetype Choices (Ship / Gun / Shield); hopefully more to come.
While it gets frantic, I can sometimes find that Zen Flow where I'm more watching what I'm doing than actually doing it (I used to get this in Killing Floor especially as Commando starting in Zed Time - not so much in KF2, though I haven't played much Commando since early on).
Great arcade game. You can jump in and play without consequence. Quit without consequence.
Yet within that game you have NAIL BITING DECISIONS AND ACTIONS. Do it. Buy the game.
D'oh.
P.S.: I had to turn the screen shake and screen flash off; I started contracting epilepsy around wave 110.
(starts with 50sec blackscreen. D`oh)