Firstly: I have played and beat all of portal and got all the achievements without any type of cheating or exploits, anyway i found an exploit on youtube to beat the Least Portals challenge on one of the test chambers (i think #15) with 0 portals. anyway i wanted to try it, and it worked. HOWEVER now it says 0 portals on my least portal challenge (cuz i was dumb enough to step into the elevator) and i don't want that on there. i want my challenges and stuff to be legit. does anyone know of a way to UNDO this? maybe undo that challenges completion flag? so i can redo it? dunno.

Go to your Steam page and click on your Portal Achievements. I believe you can clear them, though I'm not 100% sure.

In the folder
...\Steam\steamapps*your account name*\portal\portal\SAVE
you can find a file called bonus_maps_data.bmd. Open it in Notepad and change the values as you want.

Ald?z wrote:
In the folder
...\Steam\steamapps*your account name*\portal\portal\SAVE
you can find a file called bonus_maps_data.bmd. Open it in Notepad and change the values as you want.

yeah that did the trick! thanks!

msleeper wrote:
Go to your Steam page and click on your Portal Achievements. I believe you can clear them, though I'm not 100% sure.

i looked around... didn't seem to find any way to clear them through steam.