Originally Posted by Whitefeather025
Is it absolute that the only way to get every achievement is by repeating a play-through as the guide suggests, or is there anyone who has achieved them all in one go?
You will need to play the second playthrough, yeah. Only because of the level achievement, you will not be able to viably achieve level 50 on the first playthrough as enemies will stop leveling up pst the mid-30's so when you exceed that you will start to get less and less xp from them to a point where you're only getting ~1xp per kill. Considering you will need hundreds of thousands/millions of xp to get to level 50(or 61 from the Knoxx DLC achievements) you will need to kill enemies that are at/around your level.