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 ...

As Wheatley confronts you with his spikes, fire a portal through the broken wall behind him. After a moment, white gel will begin dripping onto another surface. Fire a portal beneath the drips, and a ...

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 ...

Right away you spot a red floor switch as the testchamber branches both left and right. For now, go left up the stairs (the stairs later recede into the floor, forming a pit). At the top of the stairs ...

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 ...

After entering the chamber, portal up to the platform at the other side of the room (there's a "Thank You" sign on the wall). Fire a portal beneath the Propulsion Gel tube, and another on the wall ...