You can start the game, create new characters, play it, modify settings, load and save the game etc. I have managed to play the game from start to end, clocking in at about 90 hours of play time, sometimes with play sessions of 3-4 hours uninterrupted gameplay.
Importing and exporting characters works as well.
Since the game is DRM-free, you can start it without using Steam:
wine start 'C:\Program Files\Steam\steamapps\common\Underrail\underrail.exe'
What does not
The game is written in C# and uses .NET as well as Microsoft XNA (which is the reason why it's not available for Linux/Mac in the first place), so it doesn't run without the respective winetricks addons.
xna40 via winetricks:
WINEPREFIX=/path/to/wineprefix winetricks dotnet40
WINEPREFIX=/path/to/wineprefix winetricks xna40
What was not tested
|Operating system||Test date||Wine version||Installs?||Runs?||Used|
|Current||macOS Mojave 10.14||Jun 16 2020||4.0.4||Yes||Yes||Yes||Gold||Felix|
|Show||Arch Linux x86_64||Apr 08 2019||4.5-staging||Yes||Yes||Yes||Gold||Jeronimond Xenushyre|
|Show||Ubuntu 16.04 "Xenial" amd64 (+ variants like Kubuntu)||Jul 30 2016||1.9.15||Yes||Yes||Silver||MikeMaximus|