A custom game is a customizable gametype in all of the Bungie's Halo games. There are many different custom game types available, although the player is encouraged by Bungie to make their own and to be more experienced over time. This can be done whether on local play, split-screen, or on Xbox LIVE.
 List of Gametypes
- Psythik, a user of bungie.net, has made an online custom games finder, so if someone has no friends that are playing a custom game currently, they can find a game.
- Infection is the most popular Custom Game in Halo 3, with over 100,000 variants saved.