S.T.A.L.K.E.R.: Shadow of Chernobyl may be using stolen graphical assets from other games, including Doom 3 and Half-Life 2:
One of the first threads to be made regarding the matter was posted to the MapCore forums; the thread creator, user michi.be, posted screen captures allegedly comparing the light image folders from S.T.A.L.K.E.R. to those of Doom 3 (all screen captures locally mirrored). Tellingly, though some of the images had been modified in various ways, such as having hue or saturation adjustments, the original filenames from the Doom 3 folders remained the same--for example, a file with the Doom-esque name "lights_impflash.dds," referring to one of the game's enemies, was visually modified in the S.T.A.L.K.E.R. folder but retained the filename.
ShackNews contacted Todd Hollenshead, id Software's CEO, about this issue:
I've seen a post on a web forum that claims DOOM3 assets are used in another game, but we've been working hard on Enemy Territory: Quake Wars as well as our own internal project and have not had the time to fully investigate or otherwise verify that the claim is true. Only from what I've seen on the Web, it's concerning. However, it may turn out to be nothing. Nevertheless, it would be improper to make any decision about a course of action until we find out whether the claim is true, and what assets from DOOM3, if any, have potentially been used.
He basically says they still need to investigate this matter but from his comment you can conclude that if GSC Game World, the maker of S.T.A.L.K.E.R., "borrowed" these files, they definitely didn't received approval from id Software to use them.