- Bronze: 40
- Silver: 28
- Gold: 22
22 Portal Strategy
- Proceed forward. It is not necessary to use a portal to pass the malfunctioning door, just wait to go through.
- Crouch in the right hand corner near the laser wall and aim a blue portal right above the security camera.
- Place an orange portal on the wall and proceed through so that you are standing on the security camera.
- Jump from the camera onto the next level then shoot an orange portal on the upper side wall through the laser ceiling.
- Jump back onto the camera, go through the blue portal, then proceed to the next area.
- Shoot a blue portal at the center of the small island in the right hand corner.
- Place an orange portal on the wall back towards the entrance and carefully walk through.
- From the edge of the island, aim to shoot an orange portal up and to the right at the small wall.
- Drop through the blue portal to the upper area then shoot an orange portal at the floor of the pit.
- Drop through the orange portal and land at the edge of the laser bridge.
- Walk forward and shoot an orange portal through the laser wall.
- Drop onto the floor next to the blue portal then carefully fall through it into the next area. CAUTION: Do NOT drop directly into the blue portal.
- Shoot a blue portal at the left hand side of the opposite wall as close to the corner as possible.
- Walk carefully onto the white edge of the laser floor near the wall, then shoot an orange portal on the wall directly opposite the opening above the button.
- Fall through the blue portal onto the button.
- Shoot a blue portal onto the wall and very quickly run off the button, through the portal, and shoot a new orange portal through the doors before they close.
- Go through the blue portal into the next area then proceed across the bridge.
- Shoot a blue portal on the wall next to the cube dispenser button then go back across the bridge and enter the orange portal.
- Shoot an orange portal onto the opposite wall above the ledge for the next floor.
- Push the button, get a cube, then carry it through the blue portal to the next floor.
- Use the cube to block sentry bullets, walk into the alcove, then shoot a blue portal through the energy bridge onto the upper wall behind the glass partition.
- Carry the cube back through the orange portal then run across the energy bridge and use it to knock over the sentry gun.
- Go back across the energy bridge, drop the cube on the button then go back across the bridge again.
- Shoot an orange portal downward onto the opposite wall then proceed back through the blue portal with the cube.
- Shoot a blue portal downward onto the opposite wall and proceed through the orange portal with the cube.
- Run past the lightning when it is safe then shoot an orange portal down onto the side wall.
- Go back through the blue portal with the cube.
- Kill or pass the sentry, then go through the door with the cube, but not too far.
- Place the cube directly in the center of the doorway so that it can't close all the way then proceed forward.
- Turn back towards the entrance and shoot a blue portal at the very top of the wall across from the energy barrier.
- Go back through the barricaded doorway and carefully shoot a blue portal through the orange portal, through the energy barrier, and slightly downward onto the opposite wall, then drop backwards through the orange portal before the blue one lands. (If done correctly you should be standing in front of the orange portal staring a sentry gun in the eyeball.)
- Go through the orange portal, kill the sentry, then shoot a blue portal onto the opposite wall.
- Drop down and shoot an orange portal at your feet as you fall.
- Proceed through the disintegration barrier and very quickly jump at an angle towards the three sentry guns. As long as you are quick you should be able to grab and knock them over then proceed to the exit.
21 Portal Strategy
- It is not necessary to use a portal to pass the malfunctioning door, but it is quicker. Shoot a blue portal directly ahead, onto the back wall behind the laser wall.
- Shoot an orange portal onto any nearby wall and walk through.
- Aim upwards at an angle and shoot a blue portal on either side wall, just beyond the laser bridge you can see.
- Go carefully through the portal and proceed to the next area. Note that you are now at the same point as having completed step 5 in the 22 Portal Strategy above, and have used the same number of portals (3), but without having had to crouch to aim or to jump on and off the camera.
- Stand facing the laser bridge, look downward, and shoot a blue portal on the wall of the small island in the lower right corner.
- Go back toward the entrance, shoot an orange portal on the wall, and walk through.
- Look up and to your right. Shoot an orange portal at the small piece of portal-able wall you can see there. Step through.
- Position yourself so you are facing the laser bridge, with your back to the wall. Inch out as far as you can to the right, over the drop. Crouch. Aim at the bottom corner of the laser wall (not the bridge, the laser wall you can see beyond the bridge) until you find a place you can shoot a portal through the laser wall. Shoot an orange portal there.
- Here's the tricky bit (and before trying this is a good place to save your game). Jump onto the island where your blue portal is. You need to miss the laser bridge (go under it, you can't go over) and land on the island. It IS possible.
- Step through the blue portal. At this point, you are at the same place as if you had just completed step 12 in the 22 Portal Strategy above.
- Follow the 22 Portal Strategy above, beginning at step 13. Now you are even BETTER than gold!
20 Portal Strategy
Most of the steps are the same as the 21 portal strategy except that it IS possible to skip the room with the electric field. If you crouch down on the energy field above it and move to the far back corner you can JUST make make a portal on the wall behind the acid pit that the sentry is aimed at. Now all you have to do is jump across the lake while holding the cube you have to block the sentry fire. Did you think this was going to be easy?