Ambiguous package name error
Hello, all. I'm having an error upon attempting to start the game; from what I can tell from Google, it has to do with the names of map/texture files?
Ambigiuous package name: Using 'C:\Program Files (x86)\Steam\steamapps\common\Antichamber\UDKGame\CookedPC\Maps\UT3\UDKFrontEndMap.udk', not 'C:\Program Files (x86)\Steam\steamapps\common\Antichamber\UDKGame\CookedPC\Maps\UDKFrontEndMap.udk' [OK]
I click "OK" and the splash image for Antichamber comes up for a split second and then disappears.
Some other info: I got this game through a Humble Bundle a while back and initially downloaded the installation .exe and game files through a torrent they provided because I thought I could link it with my Steam later. After finding out about the magic of Steam keys, though, I linked it to my Steam account and, after moving the already-installed folder of game info to my steamapps folder, went to install it in Steam. It read, if I recall, during the installation that it was looking for already-existing game data. Take that as you will; I have the feeling it might have something to do with this ambiguous package error.
I'm not opposed to completely deleting/uninstalling and reinstalling; I'd just like to remedy the problem with everything on my computer and not having to download it again.
Thank you in advance!