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Aliens: Colonial Marines AI fixed by a single letter


Oct 27, 2017
In a recent thread recommending the PC version of Aliens: Colonial Marines for less than $3, a post happened to single out an announcement made on the ModDB page for Aliens: Colonial Marines.

A passionate modder who has made it his mission to overhaul aspects of the absolutely dreadful Colonial Marines was working on tinkering his highly regarded overhaul mod known as TemplarGFX’s ACM Overhaul when he stumbled upon something interesting in the games .ini files.I think I’ll let him explain...
A new update will be coming soon with this change included, however after getting reports back from several players on how much this effects the game, I just had to post it now

Inside your games config file (My Document\My Games\Aliens Colonial Marines\PecanGame\Config\PecanEngine.ini) is the following line of code :

ClassRemapping=PecanGame.PecanSeqAct_AttachXenoToTether -> PecanGame.PecanSeqAct_AttachPawnToTeather

Im sure you'll notice the spelling mistake

ClassRemapping=PecanGame.PecanSeqAct_AttachXenoToTether -> PecanGame.PecanSeqAct_AttachPawnToTether

If you fix it to look like the above and then play the game, the difference is pretty crazy!

Why is this line important? There are two reasons :
1) AttachXenoToTeather doesn't do anything. Its basically empty or stripped
2) AttachPawnToTether does ALOT. It controls tactical position adjustment, patrolling and target zoning

When a Xeno is spawned, it is attached to a zone tether. This zone tells the Xeno what area is its fighting space and where different exits are. In Combat, a Xeno will be forced to switch to a new tether (such as one behind you) so as to flank, or disperse so they aren't so grouped up etc. (*disclaimer* this is inferred opinion, I cant see the actual code only bits)

Whenever the game tried to do this, nothing happened. Now it does!
Knowing full well how absurd this sounds on the surface, I took it upon myself to reinstall the PC version of the game, look at the .ini file and check myself. Sure enough, a single letter typo was found exactly where he claimed. I was in disbelief. As recommended, I fixed the typo, saved it in Notepad and booted the game up.

The improvement is immediately recognizable in your first encounters with the Xenos. While they still charge you perched on their hind legs, they now crawl far more often, flank you using vents and holes in the environment and are generally far more engaged and aggressive. Five years after release, a single letter managed to overhaul the entirety of the enemy AI behavior in the game.

While I am still a vehement detractor of Gearbox and the game itself and would recommend against picking this up for any price, if you already own the game on Steam I wholeheartedly recommend trying this out yourself. Also consider enhancing your experience with the TemplarGFX ACM overhaul mod as it brings a host of other small but noticeable improvements to the game. And while I’m here, don’t forget to give this ol’ gem a watch.

For those who were asking for it, PC Gamer put up an article with comparison videos and a firsthand account of their experience with the fix.

Spoiler: They also noticed the improvement.
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Oct 25, 2017
Reminds me of the time some users, myself included, found a simple way to fix a bunch of Halo PC shader errors / missing shaders on the Gearbox forums. They were notified of the fix and never included it themselves. This was when Halo PC was still recently released.

At least some of their people are literally incompetent.


Nov 4, 2017
Out of curiosity, how did it take this long for anyone to find this error? This game has been reworked and tweaked by modders for years now.


Oct 25, 2017
So you're telling me that part of the reason this game was such a fucking mess was because like

A single line of code had a typo in it


Oct 27, 2017
I'll always remember A:CM doomed TimeGate Studios (whose Section 8: Prejudice game was actually pretty fun in multiplayer). What a mess.


Oct 25, 2017
Games are machines. Super complex machines. And yeah like having one wrong bolt or something in a car stops the whole thing working, it's the same here
It's not that I don't understand why it happened, it's that I can't believe such a crucial and egregious element completely slipped under everyone's noses


Oct 25, 2017
I know what it's like to work with programmers that can't spell. This kind of stuff is frighteningly common. It isn't an unusual thing to see programmers that proudly display their ineptitude for language and communication, because apparently logical thinking and effective expression are incompatible.


Oct 25, 2017
Columbia, SC
Wow. The aliens gaming franchise could have potentially gone in an entirely different direction and have an entirely different history...all over a single letter being where it wasn't supposed to be.


Oct 27, 2017
I thought this was going to be a heart warming redemption story where a passionate fan had written into Gearbox to have the game fixed, and Randy took it upon himself to fix absolutely everything wrong with the game after so long.

Turns out the truth is actually even better than that. Fucking Gearbox, man.


Oct 27, 2017
I bet the guy who made the thread about getting this for 3 bucks is feeling validated now, haha