How do you Deathmatch?

By PillarNexus, in DOOM: The Board Game

For those who've created Deathmatch rules for DOOM, how'd you go about it? I keep rolling ideas in my head of how but nothing seems fair enough. Having another game (Adrenaline) around that caters to Player versus Player free-for-all combat is nice, but I'd like to make use of DOOM's combat system because I like DOOM. I'm still hoping for an expansion with Deathmatch rules, but I'd like something to try out in the meantime.