Patch V-09: higher volume levels, more credits, fewer AudioListeners — icosi-do Steam update #103885

Another day, another patch: I had a closer look at the volume levels of sounds and music, and decided to increase the internal volume levels quite substantially. You probably want to adjust your volume settings in SETTINGS > AUDIO > SOUNDS and MUSIC. Also, I cleaned up the Unity scene by removing one of the AudioListeners. And last but not least: I added some more credits to acknowledge the authors of various assets that I'm using. As always, please let me know any comments!