It sucks when you get knocked down by a flaming tank. He can stand over you and beat you to death at will, and your only hope is that your teammates will circle back and bring him down before you run out of hitpoints. Since he's on fire and destined to die, and since your getting knocked down was likely your mistake, and since your teammates stand to inherit any valuable resources you might have, the game gives them strong incentive to leg it and leave you to your pulpy fate.
It's shocking how often people put scoring and game mechanics aside to help each other. It's far more common here than in games with larger player counts.
It really is a unique game.
Shamus Young is a programmer and writer by trade, videogame nitpicker by inclination. If you have the patience for more of his ramblings, they can be found at ShamusYoung.com.