I found an awesome glitch in this game!
To activate it, you need to ignore the mechanic and go straight to Lucy the soldier.
Talk to her, you'll fight the 6 thugs as usual, then crazy stuff will start happening.
This is difficult to accomplish without cheats because the two big cannons are next to impossible solo. What you need to do is buy 8 piercing shells from Pobre Obre and fire them at the beginning of the fight. There's a slight chance the big cannon won't be able to act afterwards, or at least only act, like, one turn out of 10. If he doesn't you're screwed, try again.
Getting past the 2 cannons on your own is the mind-blowing achievement.
"As for threetimes, yep, she is a badass mofo faq maker." - ignasia7
Getting past the mutant crocodile in the sewers was worse, seriously.
I got him with Concentrated Methyl, one of the prizes from the Devil's Tower's vending machines. Then I went and beat Mr Muscle with it too. (I couldn't do it before, the main character is really underpowered on foot)