Grimrock

Because of a bug report on the ORRR3 Steam page, I have discovered:
https://itsfoss.com/steam-play-proton/
(Wine integrated into Steam; not exactly new, but maybe not everybody knows about it)

I've only tried it with LoG2 so far, in Manjaro Linux.
Briefly in the main campaign, longer in ORRR3.

I had to switch from fullscreen to borderless mode.
In fullscreen mode, the game eventually crashed with an "out of memory" error after alt-tabbing back and forth several times.
Also, parts of the champion GUI in the lower right corner turned black after alt-tabbing.

In borderless mode, there haven't been any bugs so far.

Are you using Vulkan or OpenGL? I know DXVK has some memory leaks with Direct3D 11/12 so it wouldn't surprise me if they're present with D9VK as well.

Vanilla Wine's D3D9 implementation works mostly fine with Grimrock 2, except that spot lights don't display properly at all. Performance is also not great since Windows Grimrock's renderer is so CPU-heavy (to be fair, this should at least 50% be blamed on D3D9 itself being kind of awful, not blamed on the developers).
You can of course fix both of these issues by making Grimrock 2 use its OpenGL renderer...unfortunately, the only way I've found to do that is to edit grimrock2.dat, which is far from ideal. Actually, you might want to do this even on native Windows as the OpenGL renderer, for whatever reason, has better shadows.

Many recent versions of Wine also have an xaudio2 implemenation that doesn't work properly with Grimrock 2 and causes 3D sounds to always play at full volume and balance, regardless of how far away you actually are from the sound. I believe the most recent version with a working xaudio2 for Grimrock 2 is 4.4, so that's the version I use.