Ive played a similar game once, it was called blue room.
you spawn inside that little underground room in snowbound (glitch)
It's non stop spawn kills, you're lucky if you can live for 2 seconds, no shields, 1 shot your dead (even with plasma pistol)
Crazy game, and it was a fiesta type
I actually have that map on my file share along with one called "The Glass Room" it's this tiny little room that you have no way in or out. It's in the Rat's Nest level. Pretty much a glitch but it can make some interesting and funny matches. Lob a few 'nades around and kill everyone at the same time.
EDIT: ok apparently it vanished from my file share but regardless it was a great map variant when you just wanted to goof off.