Halo's design aesthetic is mostly known for bright colors and glowing lights, and not so much for bent steel and rust. But Halo 4 is a new start for the series, and 343 Industries is trying to put its own stamp on the franchise. The concept art for a multiplayer map called Warhouse shows a bit of grime in the Halo universe.
A post from 343 on Halo Waypoint describe's Warhouse's tight corridors and half-finished construction. The gas-mining ship beat out other ideas including a jungle-bound stage or a science facility. 343 wanted the map to feel "memorable, from an interesting and unseen part of the Halo universe."
From a gameplay perspective, Warhouse is a symmetrical map tuned to Slayer. The team says they built landmarks to make it easy to find your way without getting lost, and wanted the symmetrical points to assure balance against competing teams.
We've heard the developers talk about the story from a conceptual perspective, but most of what we've seen ourselves has been related to the multiplayer -- from much of the recent in-game footage to this concept art. Microsoft and 343 have been playing the campaign pretty close to the vest for the time being, so Halo fans will have to rely on multiplayer bits for their fix.