Warhouse is a working title for this map, 343 says in the latest Halo Bulletin update. It's a smaller, symmetrical map designed for Slayer gametypes. "We wanted this playspace to be similar competition-wise to older symmetrical maps in previous Halos, so we sought influence from those, and also from the industrial close-quarters combat in more recent games," the 343 blog post reads.
There are a series of small pathways connecting various areas of Warhouse, allowing for what 343 hopes are many surprising encounters. You know, like that time that Spartan sneaked up behind you and -- well, you get the idea.