Can you play Halo 3 multiplayer online with 2 players on 1 console?
Yes. In fact, a single console can play matchmaking with up to four players. However, all players must either have a Gold Membership or be the guest of someone on the same console who does have it. Set it up by having the person with a Gold Membership log in, and then have the second player press A to log in, but instead of choosing the normal gamertag, at the bottom of the list should be a default gamertag labeled ‘Guest’.