You are born with 100 HP

As time goes on, you lose HP by the system. (Degredation)

If you are shot, you lose HP

If you shoot someone, you gain 1 HP

If you eliminate someone, you gain 2 HP

If you bust someone out of jail, you gain .2 HP

With every shot, your gun gets stronger.  The stronger your gun the more damage you do per shot.

You can fly every 5 minutes.  Someone kicking your ass? Fly out of there!

If you work together with friends or family, then when someone starts you attack you, you can all concentrate fire on the attacker and wipe them out with the quickness

You can shoot yourself to eliminate yourself from the Vday round and return back to normal game play.

Yes, the jail perk and the attack perk both work on Vday.