Think with portals. Use them to get across bottomless pits. Use them to redirect objects. Use them to transport your beloved Companion Cube.
This map is single player with 3 [leftover] observer slots.
Estimated play time from start to end: 1 hour 30 minutes. (or 2 hours if you're new to the concept)
How to play:
1. Hotkey your Gateway, Stargate, and Robotics Facility. These are your controls
Gateway - Direction of your portal gun
Stargate - Portal color (must have both present for portals to work)
Robotics Facility - Picks up and drops your Companion Cube, used for dropping on switches.