Originally Posted by ArmandAJ
Has Valve patched this glitch for the achievement? Cos ive tried it with least portals on chamber 13, it worked, but then when i returned to the level select screen all the extra challenges ie: least steps, least portals, advanced, had been removed.
Has this happened to anyone else?
Try here (was at the second page):
The point is that when you start the game, do not load a level, but instead start a new game (level). As I experienced, you can load games without loosing your progress, the only important is that you start a new game (level) when you start the game for the first time.