The Skyscape is a mirrors edge inspired btb slayer map, wherein movement is based on parkour rather than traditional halo level design. It's huge, so it's best to have as many players as possible. It works for any gametype, and was made to be especially interesting for infection once they add it, though it may require modification.
You can view a clip of its gameplay here: http://xboxclips.com/Luigi+Punch/7801f212-d617-46ca-ae76-a9d743f0d3a7
It works on slayers, strongholds, and ctf, aswell as other gametypes.