If you start Anti-Matter on Hell difficullty and die, you can not give up.
If your "now invisible" revive timer runs out, your name in the top left does change from red to black.
If you went to the ground (half-dead) befor or after Anti-Matter started but do not get revived in time and Anti-Matter is successfull, you will earn the Blood-Skin anyway.
You can not press "Give up" befor the Anti-Matter-Timer runs out. If everyone and the facility dies, you have to leave through menu, granting you no experience for that game.