Insurgency, because so far no other game nailed down their formula of simplicity, deadly gunfights and actual tactical thinking. But nowadays I wish to be into massive battles, so I just play Planetside, no matter how much the devs are trying to kill their game lmao.

But for nostalgia's sake, Battlefront 1 and 2, I used to play these with my brothers back when we were kids. I always loved these two unbalanced stupid nerd games.