Left 4 Kart is a gamemode we came up by accident with Umiman, when we were trying to see what happens when two people are off sacrificing themselves at the same time. (Both die when you push the button).
The game decided to start on the first map, so we put the game on Easy and raced as fast as we could to the end. The Kart part started with a witch that Umiman startled. He hid behind me in a closet and the witch incapped me while trying to get to him. In the next map right at the start there were two gas canisters. I blew them right as Umiman was passing them. I like to call this the "Banana Peel" technique.
Playing like this is rather thrilling and fun, as you keep fearing all the zombies catching up to you as there's no time to kill them all and it's not usually advantageous to kill a Special Infected you hear to be around (especially if they are behind you) as they make great obstacles for the other racers. The best thing is if you manage to skirt around a tank in a chokepoint leaving the others to face it.
I think the rules need some hashing out though. Outright shooting other Racers is definitely not allowed, but should blowing up gas cans or making a fire to block other's path be? Should you save fellow Racers from the clutches of Special Infected? Comments and thoughts on the matter are welcome. What I do think would be perfectly in the spirit of the sport is blowing up a Boomer to another Racer's face.
Now only if this week's Mutation would be "Room for One" so the issue of how the finales will work solved itself.
There is a "Left 4 Kart" event scheduled on Sunday on Dwarf Fortress Community. We'll gather to chat first and then see how it goes. Based on my first impression it's bound to be funTM.