Portal — Achievement Walkthrough

In chamber 17 the game forces you to drop the Weighted Companion Cube into the emergency intelligence incinerator to proceed. It's a required story step, so you'll get this just by progressing. (Sorry, cube.)

At the end of chamber 19, instead of riding the platform into the fire ('the party'), you portal off the moving platform to escape behind the scenes. Doing that — the correct 'party escort submission position' decision — is a required story beat that triggers the back-half of the game, so it unlocks naturally.

In any room with multiple turrets, pick one turret up and physically throw/launch it into another standing turret to topple it. The easiest spot is a turret-heavy chamber (around chamber 16–17): grab a turret, carry or fling it through a portal, and slam it into a second turret. The collision knocking the second turret over is the trigger.

Use the momentum (fling) trick: place a portal on a high wall/ledge and another on the floor far below, then drop into the floor portal. You exit the high portal with all that built-up speed and fly forward. Any big drop-to-distance setup works — the test chambers near the end (or the long fling rooms) are ideal. Maximise the fall height before the exit portal to launch 300+ feet.

Advanced maps are harder versions of chambers 13, 14, 15, 16, 17, 18, available from the menu after you beat the campaign. They add hazards and remove easy solutions. Work through each one — the solutions are the same core portal puzzles but with tighter execution (precise flings, faster turret handling). 'Cupcake' is 2 done, 'Fruitcake' is 4, 'Vanilla Crazy Cake' is all 6, so finishing all six gets all three. Take them one at a time; look up a specific chamber only if stuck.

Find a flat floor and a flat ceiling directly above each other (any room works). Place one portal on the floor and the other on the ceiling directly above it, then step into the floor portal. You'll fall through the loop endlessly, building distance. Just stand in the loop for a little while and you'll pass 30,000 feet. Don't move off-axis or you'll clip the edge and stop.

Scattered through the chambers are radios (the small playing-a-jingle props). Most just play music, but a specific set of them, when carried to a particular spot, switch to a static/SSTV signal — these are the hidden 'Rattmann den' transmissions added in the game's ARG update. Carry radios around the den/secret areas (the graffiti-covered hidden rooms behind movable panels) until a radio's tune changes to the transmission signal; collecting the required transmissions unlocks it. Explore the hidden behind-the-walls 'rat man' rooms — that's where the signal points are.

Throughout the chambers there are little security cameras on the walls. You can knock each one off by hitting it — drop a Companion Cube/turret on it, fling an object into it, or portal-fling yourself into it. There are a fixed number (around a dozen-plus) across the game; you must detach every one. Keep an eye out in each chamber and knock off any camera you see — a chamber checklist helps, and you can replay via chapter/chamber select to mop up missed ones before finishing.

Bronze thresholds are generous — basically just complete each Challenge chamber reasonably efficiently. Run all six challenge maps across the three categories (portals/steps/time) and hit bronze on each. This comes for free if you're going for silver/gold, so do it on the way.

Challenge mode rates chambers 13–18 on three categories: Least Portals, Least Steps, and Least Time. Gold thresholds are tight and you do them one category at a time. Portals-gold needs optimal portal reuse (place once, fling through repeatedly); Steps-gold needs efficient pathing and fling chains to cover ground; Time-gold needs fast, confident runs. Getting all gold also clears the bronze and silver achievements automatically. Optimise category by category — Least Portals is usually the trickiest, so plan portal-efficient routes.