Yea Half Life! Although it is lacking the multiplayer department I don't care because it's the awesomest single player experience ever. Also, the sequels actually do what a sequel is supposed to do and leave you wanting more and more and when you do get more it's usually either as good or better than the last part.
CoD is great because of it's multiplayer (which tbh I think MW2 had the best multiplayer, however MW1 had the best single player. MW3 suuuuuuuuuucked.), and Halo can never win because the only good Halo game was Halo 1 (and Halo Reach was kinda fun). Personally Halo's 10th Anniversary was fun as hell and felt great to play a great game that had a lovely graphical makeover, but I wish it hd more firefight maps...
CoD is great because of it's multiplayer (which tbh I think MW2 had the best multiplayer, however MW1 had the best single player. MW3 suuuuuuuuuucked.), and Halo can never win because the only good Halo game was Halo 1 (and Halo Reach was kinda fun). Personally Halo's 10th Anniversary was fun as hell and felt great to play a great game that had a lovely graphical makeover, but I wish it hd more firefight maps...