Apparently, I needed to clarify the scene of the final battle.

First up, Rofls/Alto's group are not in a Forest, a Sewer, or out in the Streets. They are in Aperture Tower, a big skyscraper owned by the Big Bad, Director David Taylor. The group managed to get to the top floor via Rocket/Flight/Energy Construct, then plunged inward to a Monster Chamber set just below the top, then pressed on to Director David Taylor's office, where they engaged him in battle, which is where you are now.