00/01 - 0 Portals - Self explanatory 02/03 - 0 Portals - Abuses the little delay of fizzling portals when picking up the gun, wall climbing and ABH // The whole level can be done with ABH alone and clear those hug gaps 04/05 - 1 Portal - Just do a seam shot to the end of the level (On the wall) and you win 06/07 - 1 Portal - Ch06 requires a portal and 07 involves wallclimbing with the radio or jumping on scaffolding and pop-outs from the wall. 08 - 0 Portals - ABH over the goo makes this easy 09 - 0 Portals - Just throw the cube through the hole above you Ch10 - 1 Portal - Various ways to do this. Door Launch/Camerafly/Wallclimb. Just pick a method Ch11/12 - 1 Portal - Involves save glitch. Abusing Portal Gun pick to shot a portal that doesnt disappear and SPD of an object to the end of the level Ch13 - 0 Portal - Wallclimbing and getting object stuck in doors Ch14 - 0 Portals - ABH off the button to get in the air and strafe to exit Ch15 - 2 Portals - Save glitch + Camera Fly to exit Ch16 - 2 Portals - Just play the game as intended Ch17 - 0 Portals - CC wallclimb and then you win Ch18 - 0 Portals - ABH the first gap and then the rest is wallclimbing with getting an object stuck in the door Ch19 - 2 Portals - Save glitch and CameraFly to the end trigger E00 - 2 Portals - Lots of wallclimbing and Save Load abuse to get past areas. 2 Portals requires to get past fence. E01 - 2 Portals - Wallclimbing and stacking (Portals are required to get past the vents) E02 - 1 Portal - The other portal is preserved from the previous level so you can do some backtracking. Rest is Wallclimbing. GLaDOS fight involves standing on railing underneath GLaDOS

The whole game involves only 15 Portals. (I'll add videos later)