Forge/Halo 2: Anniversary
From Halopedia, the Halo wiki
Forge is a gamemode featured in the multiplayer component of Halo 2: Anniversary. The iteration of Forge in Halo 2: Anniversary, like the rest of the multiplayer component, is based on that of Halo 4 and as a result carries many similarities to that featured in Halo 4.
Changes from Forge mode featured in Halo 4
Halo 2: Anniverary launched with three Forge canvases. Unlike previous Forge canvases, the canvases available in Halo 2: Anniversary feature only skyboxes and no/ little terrain, allowing players to construct terrain from scratch.
Halo 2: Anniversary also allows players to Forge structure objects on all other maps shipped with the game, effectively expanding the Forge map palette to include all rHalo 2: Anniversary multiplayer maps.