Don't post comment about mod starting issues until you try those steps:
How To Fix Hellsound Dreams (updated)
1. To make Hellsound work on Steam DELETE file "surfaceproperties_manifest.txt" from: "hellsound\Scripts\" FOLDER (full path name: "steam\steamapps\sourcemods\hellsound\scripts").
This will prevent crashing on startup.
2. Install Source SDK base 2007 from tools tab. It's a HL2/EP1/EP2 content that allows you to play Hellsound without owning any of Half Life 2 series game.
3. Have fun!
Unfinished mod :/ I like it good work
keep an eye for news :>