Intense
This game is truly intense, especially near the end. The never-ending waves of zombies, the air strikes, the helicopters, the mounting desperation of the military over you and the zombies. There are only three problems I see with this game:
1). The lag. I know it's almost to be expected for this kind of game but it gets SUPER annoying. And on the note of annoying...
2). The voice overs really start to grind on you like if, say, you keep restarting a level. Hearing the military make the same discoveries and losses over and over eventually makes one start to shout at the screen.
3). The flames. The rest of the games graphics are awesome, but the flames look blatantly 2-D. It really distorts the appearance.