kingit: GOG put wrong OpenAL32.dll into setup. They used x86 version of file instead of x64 version OpenAL32.dll (@GOG, yes, both x64 and x86 version are named OpenAL32.dll but files are not the same). 64bit GOG installer works for some only because they installed full OpenAL setup before, so game uses file from %SystemRoot%\System32\OpenAL32.dll , not the one from root of game installation folder. Either replace mentioned file in game folder with x64 version or install OpenAL.
(btw I do not own this game, friend with the same problem asked me for help so I helped him first..)