Planetside- Dont know how many people will have played this game but it was amazing. No other game online has felt like this. Persistent online warfare was pretty much the deal. Gigantic battles with hundreds of players with vehicles including tanks, jets, dropships and eventually mechs. It had 3 factions, each fighting for control of a number of continents. To have control of a continent you had to capture all the bases on it. It got much deeper than that but that's the short of it. Can remember staying up till 4 in the morning trying hard to defend a base from a joint Vanu and Terran take over. Was such an amazing feeling to eventually push them right back from inside the base. Rare that you get a game where flying a dropship full of teammates into battle is just as much fun as being one of the troops in the middle of the fight. Shame it went downhill but can only hope for a sequel.
Halo games- Might be common to hate on them these days but Combat Evolved was freaking perfect back in the day. To me and my mates it was the perfect console fps (Yes we had played Goldeneye, Timesplitters and perfect dark.). Not very many (if any) other games have made me drag tv's around town to hook up for a LAN party fueled by beer. Halo 2 practically defined the online console experience. Had it not been a success i doubt the whole thing would have picked off as much. Halo 3 and Reach are both great games, but i really see the first two as having the biggest impact on console multilayer.
Battlefield games- Pretty much been mentioned in the thread. Great teamwork, vehicles, massive battles and these days destructible environments. Pretty freaking sweet deal. Roll on battlefield 3.
