Part of the guys solution is coming out of his ass. Heres a defined look on the achievement:
This achievement will pop as soon as GRNDL-1 has been killed, in both single player and coop. If you did not obtain this achievement and you are sure you did not die, just make a new character and blast through it in 30mins, not hard.
DO NOT WORRY ABOUT OBTAINING LEVEL TOKENS. Level tokens are awarded for completing sections of a level!
There are 3 in the level:
1. After the first door you unlock in cyber space (after the first Troll fight)
2. The door right before the bridge with the two polarity enemies (camera zooms over to show them to you)
3. Defeating GRNDL-1
Just playthrough with a newly created character (defender if u wanna play it safe) and you'll be fine. :)