Forge has been one of the most awesome features of the Halo series since Halo 3, and it only got awesome-er in Halo: Reach when Bungie introduced Forge World, an enormous blank canvas in which players could design their own levels wall-by-wall.
Halo 4 cranks it up another notch, with The Forge being developed separately by Certain Affinity, the studio behind Halo Anniversary's multiplayer (among other things).
Halo 4's three Forge World maps will bring a number of changes to the editing mode. You'll now have the option to lock, duplicate, or snap objects together (with a new "magnet" system). Objects cast and accept shadows realistically now, and might even change aesthetically depending on the map.
Even more interesting are new player zones, which will allow editors to alter player characteristics in different areas of a map. Think the low-grav space sections in Halo: Reach's multiplayer.
Check out the video. What will you create? Let us know in the comments or on Twitter.