Lot's i can say, well like thousands! or maybe millions! Halo is a very poplar game series believe me.
Up to two players can play in the Co-Op Campaign mode on Halo: Combat Evolved.
The Social Slayer playlist in Halo 3 has two teams of five players each, so ten people can play at a time.
You can play two players on halo 3 with two controllers
up to 4 players if u have that many controllers but only on split screen as xbox live stopped
no halo "campaign" is a single player game
X-Box live.
you cant
Yes, you can.
No, players will not be able to play as an Elite in mutliplayer mode in Halo 4. Confirmed by 343i.
Yes, Halo Wars is a Xbox Live game, therefore you can play online against other players.
4 players can play through Xbox Live, but only 2 can play on the same Xbox 360 console.
Only in Online Campaign, Not Local Play