my achievements got reset 🙁
Fixed and I posted that in response to his losing an achievement. I dont classify it as cheating, I think of it as a shortcut. 
Just get this and unlock the achievements you want.
Whats the point of an achievement if you didn't earn it? It doesn't really do anything for you.
now if he earned them legitly, and then lost them, thats one thing, but otherwise to take a shortcut in something that is SUPPOSED to be challenging IS cheating. thats not a discussion, thats a definition. think of it how you want, but its still cheating.
I havent cheated on any of my achievements, so they are all legit, even though I used exploits to gain a few of the portal ones.
does anyone know the definition of cheating?
CHEATING IS USING SOMETHING TO GIVE YOU AN ADVANTAGE.
The exploits i used were all part of the source engine, thus I earned the achievements legitimately.
What would those be?
Well, for the Advanced Chambers, all I did was noclip to the elevator, then deactivate it once i was inside. GLaDOS didn't notice, and I still got the Vanilla Crazy Cake achievement 
*fifty cakes fall out*
Time out for a second. That wasn't supposed to happen.
That's cheating with cheat codes 
Cheating is using something, which is against the rules to be used, for your advantage.