still active

[TrzoBrz69]

which old call of duty is still active?

[dannydashgaming]

mw2

[QUAKETALLICA]

Not this one. Well you can try Steam servers, but ehh I wouldn't risk getting hacked. Not worth it. Alterware is safe but dead.

MW3 is active on Plutonium, but annoying af because most the people use controller aim assist on PC, which is more like aim bot than aim assist. Black Ops 2 has this problem too on Plutonium. However, Black Ops 2 you can play vanilla Steam servers and it's still safe.

Black Ops 1 has no aim bot ♥♥♥♥♥♥♥♥ and is safe because it had a server browser built-in originally. It has the best servers for Hardcore CTF which is super tense.

Black Ops 2 is the most alive as it's very popular. You can even get DLC maps still populated.

Call of Duty 4/Modern Warfare 1 is also still alive, but you will get a mix of bots and real players, usually way too many for the map resulting in TDM being a clusterf*ck of chaos and a meatgrinder. Though it's still good. Some servers mod it to remove the original killstreaks and make it overly complicated like the later games.

Sad thing about MW2 is: it actually was very alive up till about a year ago, when Activision basically shut down the 3rd party client keeping it alive just so they could then intentionally re-sell the very same multiplayer in their new game that year. The "Modern Warfare III" of last year is literally just original Modern Warfare 2 multiplayer repackaged. Talk about scummy killing their own game to have an excuse to re-sell it.