There's some confusion on this game so I hope this clears it up, I was confused by the game and guide so I made one as I got it as this was the 3rd to last achievement I got (as getting this unlocked my 312th stamp so technically also my 2nd to last achievement) in Rare Replay.
8 chapters need to be completed , sometimes it's just watching a cut-scene, sometimes its picking up cash, sometimes it's beating a boss, I'll list the parts that I know to better narrow it down, if yall can give me any advice as you progress I'll add it, thanks!
Also use the Achievement Tracker progress bar and have it on, it helps bunches!
Here's some cheats that will help you, enter them in the options menu:
WELDERSBENCH= Unlock all chapters
VERY EASY= Play on very easy mode
BOVRILBULLETHOLE= Have 50 lives
Chapters that need to be completed:
#1 Hangover (this is the tutorial but you only need to do the Gargole chapter of it)
#2 Bat's Tower: Bullfish's Revenge (evasive boss fight to cash)
#3 Barn Boys: Frying Tonight + Slam Dunk (cash on Frying Tonight) (pick up the cash n go through the tunnel for Slam Dunk) (note: you won't see your achievement progress bar update until you complete both of these chapters)
#4 Sloprano: The Bluff (cut-scene)
#5 Uga Buga: Buga The Knut (boss fight)
#6 Spooky: Mr. Barrel (cash)
#7 It's War: Peace at Last (cut-scene)
#8 Heist: The Vault (boss fight)