DMZ was a game mode in mw2 that was an open world-ish one-life pvp/pve that amassed a large community but was removed and has had no mentions since :(
If you want to see gameplay/tutorials I recommend the Yh channels Westie, Stodeh and Phixate
WHEN YOU INSULT DIFFERENT TYPES OF GAMERS; FORTNITE PLAYERS: NOOOOOOO, THAT’S YOU >:(; ROCKET LEAGUE PLAYERS: *REPLIES WITH MOST VILE, SOUL CRUSHING INSULTS OF ALL OF MANKIND*; COD PLAYERS: