Third Unit Industrial Facility features some rather large architecture, yet the running speeds stay high. This level really makes the player feel small, as if these structures were made for titans. It's big both inside and out, giving you a lot of running room in combat. Outer Base is the next in line. The architecture is a bit on the bland side, brush-wise, but the textures carry some of the load admirably, and the level as a whole runs very smoothly.
Refinery has an excellent secondary objective and a very good theme.
The best part about all this jumping and climbing around are the secrets you'll find along the way. The plot twist that happens here is as interesting as it is unexpected. Some of the secrets are intricate and complex, and you can climb just about everywhere in here as well. Badlands is where you'll find the airstrike marker, in a somewhat-unusual location. More of the excellent outdoor architecture and texturing is seen throughout this level, with the monster count being appreciably higher than before.