When a player takes enough damage below a set threshold, instead the death animation will play but the player won't be dead. While in this "wounded" state they stay on the ground without being able to use items or move. A player with a special syringe/EpiPen can revive wounded players. When a wounded player is revived, they stand back up with all of their items and 20hp. If they aren't revived they will bleed out for 30 seconds. When time runs out, the wounded player dies and can not be revived and must respawn/wait for the next round.
I'd prefer the option above but it would be cool if someone ripped the downed script from the old Left 4 Block gamemode. I tried to but I couldn't figure it out.