Ever just filter through images of subways / the underground, especially the in-construction bits, for just how... neat, it can be?

There's so much down there that ends up being a shoo-in for combat arenas. Especially in a game that's all about right angles and hard corners.

They feature heavily in punk media for obvious reasons, so hey, they even fit thematically! Also, we have rats, and subways definitely never ever have rats because my word no they're definitely clean places. So yeah. Neat, eh?
