Finally a working sound fix for the steam version!Alright, for copyright, disclaimer, see: http://www.oldunreal.com/cgi-bin/yabb2/YaBB.pl?num=1420982304
Open up your Rune.ini and comment out or delete the original [ALAudio.ALAudioSubsystem] section. Renaming it to ['ALAudio.ALAudioSubsystem] is enough though. You might also want to apply this change to your Default.ini file, so you won't end up in a few months if you deleted your Rune.ini file with unforseen consequences.
Grab *.int and all *.dll files but ALAudio.dll out of http://www.oldunreal.com/betatest/OpenAL_v2.4.7_Rune.7z and place it in Rune Classic\System.
Grab ALAudio.dll for Rune Classic out of http://coding.hanfling.de/ALAudio_RuneClassic_20161007.zip and place it in Rune Classic\System.
Play.
Report if something doesn't work right.
Thanks a lot, but I do have to mention a bug: if I start a new game and try to skip the intro cutscene, it crashes the game. If you wait all the way it works fine, tried starting a multiplayer server as well and saving/reloading my game and it works.
Here's what it says on the first line:
Critical: Assertion failed: sizeof(PlayingSounds)