Forge/Halo 4

Forge is a multiplayer mode featured in Halo 4. Unlike Halo: Reach, which featured a total overhaul of how Forge functioned compared to its Halo 3 incarnation, Forge in Halo 4 was based on the Reach version and did not feature so many drastic changes. Despite this, Halo 4 expanded on map creation features significantly. The mode was first shown off at RTX 2012.

Objects

 * Inclusion of Halo 4 weaponry and vehicles including Promethean weapons, the Mantis and Halo 4 Armor abilities.
 * Although most objects are the same/ similar geometry as the structures featured in Halo: Reach, the previously-Forerunner-themed objects have now been reskinned to resemble Human architecture, with white and grey paint.
 * While still based on those featured in Reach, some object dimensions have been altered slightly. For example, bridges are no wider than their Reach incarnations.
 * Map-specific objects and textures. Each Forge canvas features its own selection of unique map-themed objects (See Forge Objects).
 * Interactive objects such as deployable turrets, terminals and barricades to support the new Dominion gametype.
 * Placeable Trait Zones that allow players to have their traits changed in select areas of the map.
 * Changing an object's colour now changes the colour of the paint on the object as opposed to lights.

Object manipulation

 * Inclusion of object duplication.
 * Inclusion of a magnet system to allow players to easily snap objects to one another with little effort.
 * The addition of baked lighting systems - when players exit editor mode into player mode, the lighting now bakes shadows onto the map.
 * The object which players have selected is now highlighted green to prevent players from deleting objects by accident.

Restrictions

 * Weapons can no longer be placed down on Infection maps, due to the mode's replacement by Flood. To offset this, weapons can only be spawned via Ordnance pods.
 * Due to a glitch, the fine edit and zoom camera functionality from Reach was missing in the base Halo 4 game, making fine object placement more difficult. This glitch was corrected in the version of Halo 4 included in Halo: The Master Chief Collection.
 * Object hitboxes and object textures are misaligned on some objects, making players appear as though they are floating above the floor or unable to shoot through holes in the wall.
 * Magnets on objects were hand-placed and as such, were slightly misaligned if multiple objects were placed next to each other via magnet, requiring hand-placement of many objects.

Maps
Halo 4 with three Forge canvases, a first in the series history.
 * Erosion - an underground cave area with a UNSC interior facility attached.
 * Impact - a UNSC facility set on an asteroid, allowing for forging in a space environment.
 * Ravine - a Forerunner installation on Requiem similar in theme to past Halo levels such as Forge World.

Following user feedback that the available Forge spaces were too restrictive for map-making, 343 Industries released the free Forge Island DLC for all players in March 2013, featuring a massive skybox and flat land for Forging in an environment very similar to that of Forge World in Reach.