I like El Dudereno's idea of exploding heads, how about this:
Instead of a mode like paintball or turbo, it's a game mode similar to LTK. One shot to a limb will cause it to explode (no splash damage, just a visual explosion to reference how lots of objects explode in the original like crates and chairs
), but it affects game play, so if shot in the leg, the player is running around with one leg, if shot in both legs, the player is stuck in crouching basically so they move slow and their viewpoint is low. If shot in the right arm, then they have a mirrored slappers (as in using the left arm) only slappers to make it easier on coding if it's possible to flip the model without needing a new copy of the model. If shot in both arms then you're screwed, run for your life or purposably run towards someone so you can respawn and hope to get more kills to make that suicide not hurt your score too badly. If not possible to flip the slappers models through coding, then just make it so you can't attack. A shot to the head or upper torso will be an instakill. This would be different from LTK because you wouldn't kill the person by shooting their arm or leg, you'd have to shot their upper torso or head to kill them. I could see this becoming a very competive game mode and fun viusal if it doesn't create tons of lag. Course then again might have to be an offical gamemode where new models and/or animations could be added to remove the limbs. While I don't find this game mode to have a high chance of being added, it's still something to be considered and would have a higher chance than your original idea, and might be easier on coding, course i have no knowledge of coding gamemodes so this might be harder idk. I think this could be a very fun game mode, but that's just my opinion.