I have no clue. The mod has been out for over a year, thousands of downloads and nobody reported this before... So this issue must be rare. Wolf4SDL uses OPL2 emulator for AdLib sounds/music, possibly there is some strange interaction between that and drivers on your computer.
I have tested it on multiple Widows 10 machines and on multiple Linux distributions (x86 and ARM). I do not know how to reproduce this and without access to your machine there is no way for me to troubleshoot this.
For reference - here is a full playthrough, this is how the game should look/sound: Youtu.be
kary
Michal joined
I grew up with Half-Life and its mods and I will never stop loving GoldSource Engine. Whenever I finished a game I looked for ways of modifying it, and as a teenager I had a lot more fun when making mods/maps than when I was just playing games. My first map pack was "Kill all Greenpeace". Pretty much bunch of very poorly designed killboxes I made when i was 13. My second project was much better "Blbej Den" (moddb.com/mods/blbej-den)- It still has tons of issues, but in the end I'm pretty proud of it. After Blbej Den, I was working on a very ambitious mod called "From Beneath" (moddb.com/mods/from-beneath1), but than I went to college, life happened and It was never finished (and it never will be). I also made a Wolf3D total conversion called Brutal Death Dealer of Annihilation 3D (moddb.com/mods/brutal-death-dealer-of-annihilation-3d-bdda3d). I do Lets Plays of HL mods (mostly Czech ones since I knew the comminity and can translate them) - youtube.com/channel/UCh_t0V_zmrfAkrp_7gZPsOA