GameSpot may get a commission from retail offers. Start by moving forward to the portal gun stand. The ground will break below you, causing you to fall into the waters below. Move forward up the short ...

Continue into the next hall and press the red switch to open a section of wall, leading you to a large, open room beyond. There are many turret buddies guarding the room, and before you do anything ...

The fan-made modification to Portal 2, called Portal: Revolution, gained popularity shortly after it was released. With over 40 new test chambers, there are naturally some that players find difficult ...