1. Take some time to get used to the mouse control (it is easiest best if you keep the camera behind the buggy)
2. Enjoy the music, the billboards, and the scenery
3. Eventually make your way to the Hippie mantis (pictured below)
4. Keep going back to talk to him until you pick the correct conversation branch that leads to your purge
5. Now return to the portal by the van (where you started). You can also just push escape and “Return to Main Tube” once you have purged and the level will still be complete.