Portal Test Chamber 17 (Bonus)

This is the fifth Bonus map of the game. It is unlocked when the original Test Chamber 17 has been completed.

Hazards

 * High Energy Pellets
 * Cube Hazard

Strategy
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Portals

 * Use two portals to get into the rat hole behind the projecting panel and bring out all the security cameras.
 * Stack the cameras up in the recess where you're supposed to jump across from the last lift platform. Put the Weighted Companion Cube on top and scramble up.
 * Turn back at the edge and crouch down to pick up the Weighted Companion Cube, then you can be on your merry way.

Steps

 * This chamber has long stretches of portal-unfriendly surfaces, so there aren't many opportunities to use portal trickery to keep your step-count down. The key technique for most of the way is the "bunny hop" which lets you cover long distances in a minimum of steps.  There are tutorials online, but in essence you need to move forwards and jump, then crouch just before you would land to maximize the jump length.  With good timing, and especially with forward momentum over longer courses, you can make considerable savings in steps.
 * Check your step count at each of these points. If you are over the suggested count you probably aren't going to hit the target of 150 steps, so start again:
 * Under the cube chute: 16
 * At the first pellet wall, ready to go around the corner and run down the corridor: 32
 * In the chamber with the two emitters, at the bottom of the steps to the second corridor: 50
 * On the catwalk above the main chamber, with a view of the projecting panel: 84
 * Place your red portal on the first pellet wall as soon as you reach it. All the pellets you need will come from there, but it has to be the first wall: the second emitter shuts off as soon as either pellet is captured.
 * When you reach the catwalk, drop the cube and move out so you can see the face of the projecting panel below (your step count should hopefully be not much more than 80). You don't need a great view of the face: the idea is just that you can place the blue portal on the wall directly facing you and make the pellets deflect off the edge.  With experimentation, it's possible to bounce pellets into both of the other chambers by doing this: use very small changes of the portal position to fine-tune it.  The third receptacle is easily hit by setting a portal on the sloping face.
 * Once the three lifts are up, use portals to set the cube on friendly floor where you'll be able to see it from the lift platforms: for instance, against the wall to the right of the doorway that leads into the small side-room. Then portal yourself down. You want to be right of the doorway, but as close as you can get to the end of the portal-friendly tiles. You'll be placing a portal beside the observation window above this doorway, and you need to be aligned with that.
 * Turn back to face the wall and set your red portal beside the window, as high as possible. Shoot the blue portal at your feet, then aim your fall so you go through the floor portal again and shoot out over the lifts.  Crouch as you approach the middle platform, and do a quick back-step to brake before you fall off.
 * From the platform, turn around and shoot the red portal beside the cube. You want a corner of the cube hanging into the portal so you can grab it from the other side.
 * Carry on to the button room, using the bunny-hop where appropriate (but not for getting upstairs). Stop as soon as you're on the friendly floor.  Put the blue portal on the floor beside you, crouch and reach through to get the cube.
 * Portal across to the far side of the button. It's a short distance, but getting around obstructions can take a lot of steps.  Bunny-hop down to the switch room and finish the level.
 * Alternative strategy for the lifts It's possible to raise only two of the lifts and then do a curved jump from the second platform to the escape corridor.  The technique involves simultaneously moving forwards, strafing right and turning right.  If executed correctly it will enable you to do a beautiful, hooking turn in mid-air, in open defiance of Newton's Laws.

Time

 * Grab the cube, get up the steps and run along the two pellet corridors PDQ.
 * When you reach the catwalk above the main chamber, go to the end and use a twisting motion to fling the cube as far as you can down the side passage where the lifts are.
 * As you turn back, shoot a portal at the camera above the doorway across from the side passage. Turn back to the camera above the stairs where you just came out, and shoot the other portal at it.  Grab that camera, take it to the end of the catwalk and throw it down after the cube.
 * As you jump down into the side passage, shoot a portal at the wall opposite. Shoot the other portal at the camera from above the doorway, which should now be lying on the portal-friendly floor.  Grab the camera and carry it down to the end of the passage.
 * Stack the two cameras beside the exit ledge, put the cube on top and scramble up. Turn and crouch to retrieve your cube, and get going.

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