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Aliens: Colonial Marines has terrible AI because of one typo, which you can fix


Aliens: Colonial Marines has an almost mythic status as a bad videogame. One major issue is that the enemies – the same aliens that shredded a badass platoon of marines in the film – aren’t particularly menacing. They kind of wander around and forget you’re there. It turns out, the reason they’re so dumb is a single misspelled variable in the game’s files.

An Australian modder named James Dickinson actually discovered the bug last year, while working on his Aliens: Colonial Marines overhaul. He was scouring through the ACM configuration file, and found a line of code that looks like this:

ClassRemapping=PecanGame.PecanSeqAct_AttachXenoToTether -> PecanGame.PecanSeqAct_AttachPawnToTeather

See the problem? ‘Tether’ is misspelled, so this string doesn’t actually do anything in the game. It turns out, that’s the instruction that should let enemies know where they’re supposed to be fighting and how. 

Sure, you could fix the AI in Aliens: Colonial Marines. Or you could play one of the best FPS games on PC.

Fixing the problem is as simple as removing the extra ‘a’ that appears in that line of PecanEngine.ini, which by default you can find in the My Documents\My Games\Aliens Colonial Marines\PecanGame\Config folder, as Dickinson explains in this ModDB announcement.

This all came to light this week when a ResetEra poster recommended Aliens: Colonial Marines at its sale price of $2.80. The OP, Kraken3dfx, pointed readers to Dickinson’s mod, TemplarGFX’s ACM Overhaul. And that’s when someone noticed the announcement from last October.

I am a giant fan of all things Alien-related, and for the last 20 years or so, that has meant also being a huge fan of suffering and disappointment. So, I’m reinstalling Colonial Marines (which I own, obviously) to see for myself how the AI works with this fix applied. ResetEra user JigglesBunny has already taken it for a spin, and they say the change is obvious immediately.

Guess it’s time for another bug hunt.