Course 6 of 7
Portal 2: Mobility Gels walkthrough
The last main course: old testing spheres with bouncing and speed gels on top of everything else.
- About 30 min in the videos
- 8 parts · 32 steps
Steps from 13 text guides, 1 video to watch · checked Oct 18, 2026
What each player can do here
- Atlas carries a portal gun with a pair of blue and purple portals; the two pairs work together, so either of you can step through the other's portals.
- P-body carries a portal gun with a pair of orange and red portals; the two pairs work together, so either of you can step through the other's portals.
If your skill levels differ: Both bots carry the same kind of portal gun. Pings let you mark spots and time moves without talking, and failing costs little because a destroyed bot is rebuilt within seconds. How to split the roles
Repulsion Jumps
Part 1 of 8. Lower lifts with buttons and gel, then reach the dual door together.
- AtlasStep on the button to lower two lifts so one sits near ground level.
- P-bodyA pedestal button drops repulsion gel at ground level for the lower player to bounce onto the lift.
- AtlasStep off the button so the partner rises onto the platform, then follow through the partner's portals.
- BothBoth step into their matching chutes after the dual door to reach Chamber 02.single source
Double Bounce
Part 2 of 8. Route gel and paint through excursion funnels to reach the far platform.
- AtlasPlace a blue portal under the dispenser and a purple portal on the angled panel to start the gel route.
- AtlasPress the button so gel lands on the floor by the left fizzler.
- P-bodyBounce off the gel through the left fizzler onto the upper platform, then set an orange portal where the funnel ends.
- BothMoving the orange portal beside the nearer platform makes the funnel drop its paint onto the far platform.
Bridge Repulsion
Part 3 of 8. Build a light bridge, drop gel onto it, then cross the fizzler.
- AtlasPlace portals so a hard light bridge runs from the wall to the exit side, passing under the dispenser.
- P-bodyExtend the bridge to the pedestal button, then press it to drop blue gel onto the bridge.
- BothAfter the fizzler, the Atlas-side button drops gel through the partner's portals onto the bridge, so both can bounce across.
- BothPass through the dual door to reach the chutes.single source
Wall Repulsion
Part 4 of 8. Paint wall plates with gel and bounce between them up to the platforms.
- AtlasPortal up to the platform facing the repulsion gel dispenser to line up the bounce.
- P-bodyPaint the tall metal plate with the pedestal button so the wall takes gel for bouncing.
- BothBounce between the gel-covered plates, lined up exactly, to reach the top platform.
- BothIn part 2, repeat the painting and bounce up the walls past the fizzler to the exit route.
Where people tend to fall
- Bounce must line up with the painted wall, or the player bounces away and has to restart.
Propulsion Crushers
Part 5 of 8. Speed up on gel tracks and time the crusher run to deliver a cube.
- AtlasSet a blue portal at the ramp panel and a purple under the dispenser, then press the button to lay a track up the ramp.
- P-bodyOnce the crushers start to rise, swap the portal so the partner is launched across the gel track.
- BothWith both of you on your buttons a cube drops; one of you sets it in the receptacle and the exit opens.
Turret Ninja
Part 6 of 8. Hit turrets with a deflected laser, then fling the partner to the exit.
- AtlasSet a blue portal under the dispenser and a purple on the angled panel, then press the button to coat the runway.
- AtlasStart the ping countdown and press the button on GO to dispense the pivot cube.
- P-bodyCatch the pivot cube mid-air, fly through the purple portal, and aim the beam into the turrets.
- AtlasMove the purple portal to the suspended panel facing the exit to fling the partner over, then run the runway.
Where people tend to fall
- Losing the pivot cube at any point means restarting the chamber to earn the achievement.
Propulsion Retrieval
Part 7 of 8. Coat the floor with gel, fling the partner, then deliver a cube quickly.
- AtlasPlace a blue portal on the lower panel and a purple under the propulsion dispenser, then press the button for a gel track.
- P-bodyFire orange at the slanted panel so your partner is thrown onto the platform the button lifted.
- BothA button releases a cube from the dispenser so the partner can catch it.
- AtlasCatch the cube, run back before the platform drops, then place it in the receptacle beside the fizzler.
Where people tend to fall
- The platforms only stay up for about fifteen seconds, so the cube run back must be fast.
Vault Entrance
Part 8 of 8. Kill the turret, cross the chasm, and reach the vault door together.
- AtlasDash to the red button at the door to drop blue gel onto the turret and kill it.
- P-bodyAfter the turret is handled, bounce across the room on blue gel and place a portal on the angled panel under the dispenser.
- BothPropulsion gel sails through the four portals onto the ground, then bounce on blue gel over the chasm to the walkway.
- BothA cube sliding down the incline breaks a laser to raise a gap platform, and both players must reach their switches together.
- BothSpeed along the propulsion gel, spring off the repulsion gel up to the vault door, and gesture there to work the lock.
Where people tend to fall
- Turret bullets can kill the player at the red button, so back up after pressing it.
Extras and notes
- Talent Show (Chamber 06 (Turret Ninja)). Finish the chamber without losing the pivot cube to earn the achievement.
- You Saved Science (Vault Entrance). Earned automatically at the vault door once the course reaches its end.
Sources (14)
Steps compiled from 13 text guides, checked Oct 18, 2026, and written in our own words. The videos are there to watch each part; they are not counted as sources for the steps. We did not play the game for this guide. A step marked “single source” rests on one guide so far.
- AnthyDaBeist: 【Portal 2 Coop】Full Game Walkthrough (+Extra Chambers) (Mobility Gels from 1:27:38)
- Steam Community guide by rjwut, The Comprehensive Guide to Portal 2 (Wayback copy)
- Gamer Guides, Portal 2 co-op Course 5 Test Chamber 1 (Wayback copy)
- Gamer Guides, Portal 2 co-op Course 5 Test Chamber 2 (Wayback copy)
- Gamer Guides, Portal 2 co-op Course 5 Test Chamber 3 (Wayback copy)
- Gamer Guides, Portal 2 co-op Course 5 Test Chamber 4 (Wayback copy)
- Gamer Guides, Portal 2 co-op Course 5 Test Chamber 5 (Wayback copy)
- Gamer Guides, Portal 2 co-op Course 5 Test Chamber 6 (Wayback copy)
- Portal Wiki, wiki-c5-6.md
- Gamer Guides, Portal 2 co-op Course 5 Test Chamber 7 (Wayback copy)
- Gamer Guides, Portal 2 co-op Course 5 Test Chamber 8 (Wayback copy)
- Portal Wiki, Cooperative Testing Initiative
- Gamer Walkthroughs, Portal 2 co-op: Chapter 5
- GamesRadar+, Portal 2 co-op video walkthrough, page 5 (Course 5: Mobility Gels)