At an evening event in LA tonight, Bungie confirmed that the Firefight co-op multiplayer mode from Halo 3: ODST would return in this year's Halo: Reach.
It will be expanded and improved with new gametypes, the implementation of full Xbox Live matchmaking support, and deep customisability via the in-game editor.
Check out this colourful Firefight in Halo: Reach screenshot gallery.
The new modes, which Bungie has used the editor to create, include a more "crafted" and shorter default Firefight mode; Firefight Classic, which has the same settings as ODST; Generator Defense - a variant of the beta test's Network Test 1; and the chaotic Rocketfight in which all loadouts feature rocket launchers with infinite ammo.
Unlike ODST Firefight, the Reach version will be supported by full matchmaking and all the networking features of Reach multiplayer, including Active Roster, Queue-Joining, four-player co-op over live and two-player split-screen per console.
You'll be able to create and share your own Firefight modes, tweaking parameters such as wave properties, match duration, custom skulls, Spartan loadouts and settings including health and jump height, weapon drops, and where generators are located.
Wave traits include the "shootiness" of enemies and how powerful they are; as an example, you could set up a mode in which you face infinite waves of ultra-powerful Grunts.
Any modes you create can be shared with friends and the wider Halo community by uploading them to your file share.