I was thinking maybe a Purge fun round? The round would be basically a free for all deathmatch with all weapons. Thats pretty much it.
I like how this thread basically got beat up so bad but when someone else suggests a deathmatch fun round plus 1s abound RiP @Senpai Vesper Kagetane | SF
Please just search for death match fun round or free-for-all fun round. You'll see this has been suggested before.
As Mango said, you essentially are suggesting a deathmatch game mode, which has been suggested many times before. Also, if you want deathmatch, I feel like you should just go play CSS.