Hey!
I finally decided to give POL a try after resorting to dual booting for the past. Setting up Steam worked absolutely flawlessly, as did installing Darkest Dungeon. It didn't run at first, but I could fi that by simply installing the vcrun2013 extension.
In principle, the game works well, but I have issues with sound crackling and stuttering intermittently. I found quite a few threads mentioning similar problems, but I couldn't get it to work just yet.
I am using an onboard soundchip, and I'm running PulseAudio for Plasma 5. When running pavucontrol while POL Steam is opened, I have an additional playback device there, named "ALSA plug-in [wine-preloader]: ALSA Playback on". As soon as I start Darkest Dungeon, I get two more of these - one of them disappears as soon as the intro cinematic finishes playing, so I assume that is some kind of adapter for pre-rendered videos.
The intro cinematic runs fine. When I go ingame, however, the stuttering starts. Whenever a stutter occurs, The "ALSA plug-in" in pavucontrol flickers off and on briefly, and the debug log outputs "ALSA lib pcm.c:7963:(snd_pcm_recover) underrun occurred".
Now, I understand POL doesn't officially support PulseAudio, and I tried the the BEFORE_WINE flag with pasuspender and papsd, both didn't change anything. I then removed pulseaudio-alsa and killed pulseaudio manually to ensure pure ALSA playback, but still, the problem persists.
Even more confusingly, Legend of Grimrock (started through the same POL Steam instance, not using the native Linux client) works perfectly fine. I'm at a loss and would greatly appreciate any input, because I no longer know what else to try!