Advanced Maps and Challenges
Beating Portal unlocks two categories of bonus content: Advanced Maps and Challenge Maps. Both are built from Test Chambers 13 through 18, reworked for experienced players. Advanced Maps add harder puzzle layouts. Challenge Maps keep the original layouts but impose performance constraints.
You access both from the main menu under Bonus Maps after completing the campaign.
Advanced Maps
Advanced versions of six test chambers. The core puzzles remain the same, but the rooms are redesigned to be tighter, less forgiving, and sometimes disorienting. Portalable surfaces are reduced, hazard placement is meaner, and spare cubes are removed. Every advanced map is solvable with the same techniques you learned in the main game. The difficulty comes from having less room for error.
Chamber 13 Advanced
The Energy Pellet routing puzzle from the base game, but with fewer portalable surfaces and a tighter geometry. The pellet receptor is harder to reach, and the angles require more precise portal placement.
Key change: The large portalable wall from the original is replaced with a narrow strip. You need to hit a much smaller target with your portal to route the pellet correctly.
Chamber 14 Advanced
The multi-level catwalk room. In the advanced version, several catwalks are removed or shortened. Gaps that you could walk across in the original now require flings. The cube is placed in a less convenient location.
Key change: The path from the cube to the button requires a momentum fling instead of a simple walk. The portalable surface for the fling is on the ceiling, not the wall.
Chamber 15 Advanced
The double fling chamber, made worse. The pits are the same depth, but the target platform is farther away and smaller. You need near-perfect portal placement and trajectory control.
Key change: The landing platform is narrower. Midair strafe corrections (A / D while airborne) are mandatory to hit it.
Chamber 16 Advanced
The turret chamber with reduced cover. More turrets, fewer cubes, and portalable surfaces are rearranged so you cannot use the same behind-the-back approach as the original.
Key change: Turrets are positioned to cover each other. You need to disable them in a specific order to avoid crossfire.
Chamber 17 Advanced
The Companion Cube chamber, extended. Additional turret sections and a longer Energy Pellet routing sequence. The Companion Cube still needs to be incinerated at the end.
Key change: The turret corridor has overlapping fields of fire. Using the Cube as a shield requires constant repositioning.
Chamber 18 Advanced
The hardest advanced map. Everything from the original Chamber 18 with additional turrets, fewer portalable surfaces, and a more demanding final fling. Most players consider this the hardest content in Portal.
Key change: The final fling target is above and behind you. You need to place a portal on the ceiling and fling upward, then place a second portal while airborne to redirect.
Advanced Map Achievements
| Achievement | Requirement |
|---|---|
| Cupcake | Beat any two advanced maps. |
| Fruitcake | Beat any four advanced maps. |
| Vanilla Crazy Cake | Beat all six advanced maps. |
Advanced maps do not need to be completed in order. If one map is giving you trouble, move on to a different one. Cupcake and Fruitcake pop as soon as you hit the count, regardless of which maps you chose.
Challenge Maps
The same six chambers (13 through 18) from the base game, but scored. Each chamber tracks three performance metrics, and you earn Bronze, Silver, or Gold medals based on your results.
Challenge Categories
| Category | What It Measures |
|---|---|
| Least Portals | Total number of portals fired to complete the chamber. |
| Least Steps | Total footsteps taken (each ground movement tick counts). |
| Least Time | Total seconds from start to finish. |
Each chamber has its own medal thresholds for each category. That means 18 individual medal slots per chamber (3 categories × 3 medal tiers) across six chambers.
Medal Thresholds
The thresholds are hardcoded in the Source engine. Here are the exact targets for every chamber and category.
Least Portals:
| Chamber | Bronze | Silver | Gold |
|---|---|---|---|
| 13 | 9 | 5 | 4 |
| 14 | 6 | 4 | 2 |
| 15 | 23 | 21 | 14 |
| 16 | 9 | 4 | 2 |
| 17 | 4 | 3 | 2 |
| 18 | 30 | 25 | 16 |
Least Steps:
| Chamber | Bronze | Silver | Gold |
|---|---|---|---|
| 13 | 30 | 20 | 10 |
| 14 | 55 | 20 | 10 |
| 15 | 75 | 65 | 55 |
| 17 | 215 | 175 | 150 |
| 18 | 150 | 120 | 85 |
Chamber 16 Least Steps thresholds are not listed because its step counts depend heavily on cube manipulation and crouch positioning, which cause the engine's friction calculations to vary. The other five chambers have absolute, hardcoded thresholds.
Least Time:
| Chamber | Bronze | Silver | Gold |
|---|---|---|---|
| 13 | 0:40 | 0:30 | 0:19 |
| 14 | 0:50 | 0:20 | 0:10 |
| 15 | 1:45 | 1:25 | 0:54 |
| 16 | 1:10 | 1:00 | 0:52 |
| 17 | 2:20 | 1:45 | 1:27 |
| 18 | 2:10 | 2:00 | 1:13 |
Advanced Maps vs. Challenge Maps
A common point of confusion: these are two different things that share the same six chambers.
- Advanced Maps have physically altered geometry. Portalable surfaces are removed, pits are extended, and hazard placement is rearranged. You need to solve a harder version of the puzzle. Completion unlocks the Cupcake/Fruitcake/Vanilla Crazy Cake achievements.
- Challenge Maps keep the original, unmodified chamber geometry from the campaign. The puzzle is identical. Your performance is scored against the medal thresholds above. Completion unlocks the Basic Science/Rocket Science/Aperture Science achievements.
Challenge Difficulty Ranking
From easiest to hardest across the community:
- Least Portals (easiest). Study the chamber, plan your portal placements, and execute. Reloading saves does not add portals. Take your time.
- Least Time. Requires fast execution but is forgiving of non-optimal routes. Quick-save aggressively. Accelerated Back Hopping (see Puzzle Mechanics) is practically mandatory for Gold Time on Chambers 14 and 18.
- Least Steps (hardest). Every footfall counts. Requires bunny hopping, crouch-jump optimization, and sometimes pixel-perfect positioning to avoid extra steps.
Least Steps Strategies
The Least Steps category is where most players hit a wall. Here are the techniques that make Gold medals possible:
- Use floor portals to travel. Firing a portal on the floor and dropping through it covers distance without registering any steps. This is the single most important technique for step reduction.
- Bunny hop constantly. Jumping does not count as a step. Chain jumps by pressing jump the instant you land. Every second of walking registers multiple steps.
- Crouch-jump for distance. Press jump followed immediately by crouch (
Ctrl). This pulls your feet up and extends airborne distance, reducing the number of ground contacts. - Throw objects instead of carrying them. In Chamber 13, throw the cube toward the button from a distance instead of walking it over. You save every step the walk would have cost.
- Mind the elevator. Exiting the starting elevator naturally registers about five steps. For Chamber 13, where Gold is 10 steps, that means you have roughly five steps of budget for the entire puzzle. Place a portal on the floor immediately after exiting the elevator to start saving steps from the very first second.
Challenge Map Strategies
General tips:
- Quick-save constantly. Press
F6before every risky move. If you waste a portal or take extra steps, reload (F7) and try again. Medal scores track from the start of the map, so reloading a save is free. - Plan before executing. For Least Portals, walk through the chamber mentally and count the minimum portals needed. Check community solutions if you are stuck on a Gold target.
- Ignore categories you are not targeting. Going for Gold Portals? Do not worry about steps or time. Focus one category at a time per chamber.
Chamber-specific notes:
| Chamber | Easiest Gold | Hardest Gold |
|---|---|---|
| 13 | Least Portals (4 portals is tight but logical) | Least Steps (10 steps with a 5-step elevator tax) |
| 14 | Least Portals (2 portals in an open room) | Least Steps (10 steps across multiple elevations) |
| 15 | Least Time (double fling is fast when clean) | Least Steps (55 steps with fling landings adding contacts) |
| 16 | Least Time (turrets go down fast with good portals) | Least Steps (turret avoidance paths add footwork) |
| 17 | Least Time (1:27 if you know the Companion Cube route) | Least Steps (150 steps in the longest chamber) |
| 18 | Least Portals (16 portals is complex but countable) | Least Steps (85 steps across the longest traversal) |
Challenge Map Achievements
| Achievement | Requirement |
|---|---|
| Basic Science | Earn Bronze medals on all Portal challenges (all 18 slots). |
| Rocket Science | Earn Silver medals on all Portal challenges (all 18 slots). |
| Aperture Science | Earn Gold medals on all Portal challenges (all 18 slots). |
Aperture Science (all Gold medals) is the hardest achievement in Portal at roughly 1.4% global unlock rate. Least Steps Gold on Chambers 13 and 17 pushes most players to their limit. Quick-save every few seconds. Be patient. Community video guides show the exact bunny hop routes for every chamber if you get stuck.
Commentary Mode
Completing the game also unlocks Commentary Mode. Replay the entire campaign with floating speech bubble icons placed throughout the levels. Walk up to one and press your use key to hear a developer explain why a specific design decision was made.
Commentary mode covers:
- Why specific chambers teach specific mechanics.
- How playtesting shaped the difficulty curve.
- The design philosophy behind GLaDOS's dialogue pacing.
- Technical details about the Source engine portal rendering system.
- How the Companion Cube became a cultural icon despite being a box with a heart on it.
Commentary mode does not affect gameplay or achievements. It is purely educational, and it is fascinating if you have any interest in game design.