Some ideas
Didn't play out as I planned, far too fast. might make it a 5 min map. Ideas: For the first few minutes radiation safeguard prevents radiation damage below 10HP. increase the tickets a lot and give the players plenty of chance to respawn maybe 2-3 times, But they respawn as zombies with only 10 hp who have to try and overcome the 200HP monsters before the time runs out. Might have to display the HP leader somewhere.
Might put this on the backburner for now. There are lots of things that could make the mode more fun, but take work. e.g. weapon restrictions.