Puzzle Mechanics

Portal 2 builds on the original game's physics with six major new systems: gels, lasers, Hard Light Bridges, Excursion Funnels, Aerial Faith Plates, and new cube types. Every puzzle in the game is a combination of these elements with the portal gun. Learn how each one works and the solutions come down to figuring out the combination.

Portal Placement Rules

The core rules from Portal 1 carry over unchanged:

• Blue portal on left click, orange portal on right click. One of each active at any time.
• Portals stick to flat, light-colored surfaces. White Aperture Science panels are the standard.
• Momentum carries through portals. Speed and direction are preserved relative to the exit portal's orientation.
• Emancipation Grills erase both portals and destroy carried objects.
• Portals are two-way. Objects and players pass through in both directions.

What is new in Portal 2:

• Conversion Gel creates portalable surfaces. Any wall, floor, or ceiling coated with white Conversion Gel accepts portals, even surfaces that normally reject them. This is the primary way to create new portal locations in Old Aperture (Chapters 6 and 7).
• Some surfaces have changed. Portal 2 uses a slightly different set of panel textures. If your crosshair shows the portal outline, the surface works. If it does not, it will not.

Momentum and Flinging

Same physics engine, same rules. Fall into a floor portal, launch out of a wall portal at the speed you built during the fall. Deeper drops produce faster launches.

Portal 2 gives you more tools to build speed:

• Propulsion Gel runways. Coat a floor with orange gel, sprint across it, and hit a portal at the end. You enter much faster than a normal run.
• Repulsion Gel chains. Bounce off blue gel into a portal for extra vertical speed.
• Aerial Faith Plate launches into portals. A Faith Plate can throw you into a portal at a fixed speed, which then redirects you based on the exit portal's angle.

tip

When a puzzle combines gel with flinging, coat the surface first, then set up your portals. Trying to place portals while sliding on Propulsion Gel is possible but much harder than doing it from stable ground.

Thermal Discouragement Beams

Lasers. A red beam fires from an emitter and travels in a straight line until it hits a surface, an object, or a catcher (receptor). When a beam connects to its catcher, it powers a mechanism: a door, a platform, a bridge emitter, or another device.

Rules:

• Lasers travel in straight lines and cannot bend on their own.
• Lasers pass through portals. Fire one end of a portal pair into the beam's path, and the beam exits the other portal in a new direction.
• Lasers pass through glass and grated surfaces but not solid walls.
• Lasers burn you on contact. Walking through a beam deals damage. Sustained contact kills you.
• Multiple catchers can exist in a single room. Each one needs its own beam.

Discouragement Redirection Cubes

The primary tool for redirecting lasers. These cubes have a built-in lens that catches a laser beam and re-emits it from the opposite face.

How to use them:

1. Pick up the cube and carry it into the beam's path.
2. The cube catches the beam automatically.
3. Rotate the cube by changing your facing angle while holding it. The beam follows.
4. Aim the redirected beam at the catcher.
5. Set the cube down. It holds position and keeps the beam connected.

You can chain multiple redirection cubes to route a beam around corners, through portals, and across rooms. Some puzzles require three or four cubes in sequence.

warning

Dropping a Redirection Cube while it is actively redirecting a beam can send the beam in an unexpected direction. Set the cube down gently on a flat surface. Throwing it scatters the beam.

Hard Light Bridges

Flat, solid surfaces made of light. They extend from wall-mounted emitters and travel in a straight line until they hit a solid surface. You can walk on them, crouch behind them, and use them to block hazards.

Rules:

• Hard Light Bridges pass through portals. Place a portal in the bridge's path, and the bridge extends out of the other portal in the new direction.
• Bridges block turret fire. Stand behind one and turrets cannot hit you.
• Bridges block laser beams. A bridge between a laser and its catcher cuts the connection.
• Bridges serve as floors over toxic goo and pits. Place a portal on a wall above a gap, redirect the bridge through it, and walk across.
• Bridges do not move objects. They are static surfaces. Objects placed on them stay put.

Common uses:

• Creating walkways over goo or bottomless pits.
• Shielding yourself from turret fire.
• Building platforms at specific heights by redirecting the bridge through portals at different elevations.
• Blocking and unblocking laser paths to activate mechanisms in sequence.

Excursion Funnels

Tractor beams. Wide, cylindrical tubes of blue light that carry players and objects in one direction. They emit from wall-mounted devices and travel until hitting a solid surface.

Rules:

• Standing in a funnel moves you in the direction it flows. You float. You cannot walk while inside a funnel, but you can aim and fire portals.
• Objects placed in funnels float and travel with the flow. Cubes, turrets, and even gel drops move through funnels.
• Funnels pass through portals. Place a portal in the funnel's path, and it extends from the other portal.
• Polarity reversal. Some chambers have buttons that reverse the funnel's flow direction. Press the button and everything in the funnel starts moving the opposite way.
• Funnels do not damage you. They are safe to enter and exit.

Common uses:

• Floating across gaps that are too wide to fling.
• Transporting cubes to locations you cannot carry them to on foot.
• Reversing direction mid-flight to reach platforms above or below the funnel's default path.
• Combining with portals to create vertical elevators or redirect horizontal funnels to vertical ones.

info

Funnels move you slowly. If a puzzle feels like it is taking too long, you are probably not meant to ride the funnel the entire distance. Look for a portal shortcut that lets you enter the funnel closer to your target.

Aerial Faith Plates

Spring-loaded catapults embedded in the floor. Step on one and it launches you along a fixed parabolic arc. You cannot control the trajectory once airborne.

Rules:

• Faith Plates launch players and objects. Step on one, get launched. Drop a cube on one, it gets launched too.
• The arc is fixed. Every Faith Plate has a predetermined landing zone. You always land in the same spot.
• You can place portals at the landing zone. The Faith Plate throws you, and you enter a portal at the top of the arc or at the landing point, redirecting your momentum.
• Some Faith Plates are mounted on walls or ceilings. These launch you horizontally or downward.

Common uses:

• Crossing large gaps without fling setups.
• Launching cubes to elevated positions.
• Chaining Faith Plate launches with portal redirections to reach areas neither tool can reach alone.

Mobility Gels

Gels are paint-like liquids that coat surfaces and change their physical properties. They pour from ceiling-mounted pipes and dispensers. Once a gel hits a surface, it stays until washed off with water (Cleansing Gel) or the surface passes through an Emancipation Grill.

Repulsion Gel (Blue)

Bounces anything that contacts the coated surface. The bounce height is proportional to the incoming speed. Fall from higher, bounce higher.

Rules:

• Coating a floor with blue gel turns it into a trampoline. Walk onto it and you bounce lightly. Fall onto it from height and you launch upward.
• Coating a wall with blue gel bounces you away from the wall on contact.
• Cubes and turrets bounce off blue gel surfaces.
• Crouching while standing on blue gel suppresses the bounce. Useful for positioning without launching yourself.

Propulsion Gel (Orange)

Accelerates anything moving across the coated surface. Walking on orange gel turns a stroll into a sprint. Running on it builds speed fast enough to cross large gaps with a jump at the end.

Rules:

• Coating a floor with orange gel creates a speed runway. You accelerate rapidly while moving across it.
• Coating a ramp or angled surface with orange gel launches you off the edge at high speed.
• Cubes slide across orange gel instead of stopping.
• Combining orange gel with portals is the fastest way to build speed for distance flings in the Old Aperture chapters.

Conversion Gel (White)

Makes any surface portalable. The most strategically important gel in the game.

Rules:

• Any wall, floor, or ceiling coated with white gel accepts portal placement. Metal panels, concrete, dirt, rusty pipes. Anything.
• White gel is your primary tool in Old Aperture (Chapters 6 and 7), where almost no surfaces are portalable by default.
• White gel dispensers are always positioned to let you coat specific surfaces. If you cannot reach a dispenser, redirect its output through portals or funnels.

Cleansing Gel (Water)

Washes all gel off surfaces. Pours from certain pipes and dispensers. Passing through an Emancipation Grill also removes gel from objects and surfaces near the grill.

Rules:

• Water removes any gel it touches. Blue, orange, or white gel washes away on contact with water flow.
• Useful for resetting surfaces. If you coated the wrong area, find a water source to clean it.
• Some puzzles require you to wash gel off a surface to change how that surface behaves.

Gel Interaction Rules

• Gels travel through portals. Redirect gel output through a portal to coat a distant surface.
• Gels travel through Excursion Funnels. A funnel can carry gel drops to surfaces the dispenser cannot reach directly.
• Only one gel can coat a surface at a time. Applying a new gel replaces the old one.
• Emancipation Grills destroy gel on surfaces and objects that pass through them.

tip

When you enter a room with gel dispensers, look at the dispenser positions first. Where the gel can reach tells you where the puzzle wants you to go. Place portals to redirect gel before trying to redirect yourself.

Cubes

Portal 2 has four cube types, up from the original game's two.

Cube Type	What It Does
Weighted Storage Cube	Standard cube. Holds down buttons, passes through portals. Same as Portal 1.
Weighted Companion Cube	Storage cube with hearts. Mechanically identical. Returns in a brief but memorable scene.
Edgeless Safety Cube	A sphere. Rolls freely. Fits into rounded receptacles that flat cubes cannot activate. Cannot sit on standard floor buttons.
Discouragement Redirection Cube	Has a built-in lens. Catches and redirects Thermal Discouragement Beams. See the laser section above.

Frankenturrets

A turret fused with a Storage Cube. It walks around on stumpy cube legs and makes distressed turret sounds. Frankenturrets function as weighted objects: pick them up and place them on buttons. They appear only in Chapter 5 during a brief sequence in the turret manufacturing area.

Sentry Turrets

Same behavior as Portal 1 with minor visual updates:

State	Behavior
Idle	Closed chassis, red laser sweeps in a search pattern.
Alert	Opens chassis, says a voice line, fires within half a second.
Disabled	Tipped over. Fires randomly for two seconds, then shuts down.

Turrets tip over from any physical contact: portal tricks, cube drops, or walking behind them and pushing. Hard Light Bridges block their fire. Excursion Funnels can lift turrets off the ground and disable them.

Portal 2 introduces Defective Turrets in Chapter 5. They look like standard turrets but are broken: they cannot fire, they tip over on their own, and they speak in a confused monotone. Defective turrets are plot devices, not puzzle threats.

info

Turrets in Portal 2 are less common than in Portal 1. They appear mainly in Chapters 2, 5, and 8. When they show up, the room always has a tool to deal with them: a Hard Light Bridge, a cube, or portal surfaces behind the turret line.

Emancipation Grills

Same as Portal 1. Translucent blue barriers that:

1. Erase both active portals.
2. Destroy physics objects carried through them (cubes, turrets).
3. Remove gel from surfaces and objects near the barrier.

Portal 2 uses grills more aggressively. Some puzzles require you to complete actions on one side of a grill, then intentionally walk through it to reset your portals before setting up a new configuration on the other side.

Toxic Goo

Brown-green liquid. Contact kills you. Cubes dissolve. Same as Portal 1.

In Portal 2, goo appears frequently in the Old Aperture chapters and in Wheatley's test chambers. Hard Light Bridges are the primary tool for crossing goo-filled areas.

Advanced Movement

These techniques are not needed for the main campaign but are useful for speed and challenge completions:

• Crouch-jumping. Jump and immediately hold crouch to pull your feet up. Gains extra clearance on ledge landings and extends airborne distance.
• Gel speed boosting. Sprint across Propulsion Gel, jump at the end of the runway, and enter a portal. The gel speed carries through the portal for maximum launch distance.
• Funnel hopping. Enter an Excursion Funnel, fire portals while floating, and drop out of the funnel at the exact right moment. Useful for reaching platforms adjacent to the funnel path.
• Faith Plate portal combos. Let a Faith Plate launch you, then place a portal in your landing zone mid-flight. You enter the portal with the Faith Plate's momentum and exit wherever the other portal is aimed.
• Reportal. A speedrun technique. Fire a portal beneath you while standing, then immediately fire the other portal on a distant surface. You fall through the floor portal and launch from the wall portal. Faster than walking to a pit and dropping in.

Developer Console

Portal 2 runs on the Source Engine, which includes a developer console for debugging, experimentation, and modding. The console is not enabled by default.

Enabling the console:

1. Open Options > Keyboard/Mouse.
2. Set Allow Developer Console to Enabled.
3. Press the tilde key (~) during gameplay to open the console.

Cheat commands require sv_cheats 1 to be entered first. With cheats enabled:

Command	What It Does
noclip	Disables collision. Fly through walls and geometry freely.
god	Infinite health. Turrets, lasers, and goo cannot kill you.
notarget	Turrets ignore you completely.
sv_portal_placement_never_fail 1	Forces portals to stick to any surface, bypassing the white-panel requirement.
ent_create_portal_companion_cube	Spawns a Companion Cube at your crosshair.
ent_create_portal_weighted_cube	Spawns a Weighted Storage Cube at your crosshair.
portal_draw_ghosting 0	Disables the X-ray outline of portals through walls. Used by the mapping community for cleaner visuals.

warning

Enabling sv_cheats disables Steam achievements for the current session. Restart the game without cheats to re-enable achievement tracking.

Cut Content

Two gel types were developed for Portal 2 but removed before release. Their code partially remains in the engine's files.

Adhesion Gel (Purple)

Originally designed to let players walk on walls and ceilings. The mechanic was inherited from the student project Tag: The Power of Paint, which Valve hired the team behind. Adhesion Gel was fully cut during playtesting because players experienced severe nausea and spatial disorientation when trying to calculate portal trajectories while inverted on ceilings.

Reflection Gel

Introduced quietly into the file architecture during the Peer Review DLC update, replacing the obsolete Adhesion Gel code. Leftover data shows that objects coated in Reflection Gel would ignore the kinetic effects of Propulsion Gel, bringing rapidly sliding objects to an immediate stop. This gel uses the same visual texture as Conversion Gel but functions differently. It was never exposed to players in any official content.

Speedrunning Techniques

The Portal 2 speedrunning community is highly active. The current Any% world record sits at approximately 38 minutes. These techniques are used by competitive runners but are not needed for casual play.

• Portal bumping. An exploit where you place a portal, move to a calculated position, and fire a new portal that "bumps" through solid surfaces using the engine's portal-placement collision logic. Custom map developers prevent this with func_portal_bumper volumes.
• Save glitching. Rapidly saving and loading at precise frame intervals during map transitions tricks the Source engine's state machine into skipping narrative sequences, dialogue triggers, or entire physical sections of the environment.
• Player Physics Deformation (PPD). Abusing entity collision (especially with Frankenturrets) to manipulate the player's collision hull. Allows impossible skips by combining air strafing with mid-air object interactions.
• Crouch flying. Manipulating the internal collision hull and momentum to glide across massive gaps without losing altitude. Considered one of the more accessible advanced techniques for new runners.