Amazingly adictive
This game is very addicting. Not only in gameplay, but the sounds, too. They fit the style well.
My only complaints are the health-blood thing and lack of health powerups.
You should either make health powerups, or make your health slowly regenerate. Having the screen 90% hidden is not fun at all...
You can keep the same feel without complaints if you have health regenerate, like most RTS games do nowadays. They coat the screen in blood to let you know if your about to die, and that goes away after a while. It'd fit this game perfectly, since most of the time, when you get hit by a large group of bullets or a flame thrower dude, you're gunna die anyways. Slow recharge, or fast recharge after no damage for a period of time is the way to go.
Brilliantly animated and coded. Very well done.