Most everything with one caveat.
What does not
Game controllers behave strangely; can't use a PS3 controller, even with xboxdrv. Occasionally sound screws up. See notes.
What was not tested
N/A, did a full playthrough in wine for all the endings.
Sound sometimes is missing. Rather oddly, I found two ways to fix it, neither pretty: 1) Run 'winetricks --force xact_jun2010' prior to running, every single time. I have no clue why this works. I'm also not sure it even needs microsoft's xact to play sound. 2) Launch once, keep on title screen. Go to 'C:\users\\Temp', and copy the IXP100 folder somewhere safe. This is the actual game's data as extracted via the shim. You can run the game via UNDERTALE.exe in there instead of the shim exe. Additionally, you can delete the d3dx9_42.dll in there which is not useful on Wine where one wants to use wine's runtimes. Sound works fine launching from an extracted game, strangely. You can do #2 with the steam version. iT requires an extra step; deleting steam_api.dll will make the game think it's the DRM-free version. I'm not sure how okay this information is. Steam will no longer log your playtime, of course. There's no achievements, but there are playing cards, so...
|Operating system||Test date||Wine version||Installs?||Runs?||Used|
|Show||Fedora 23 x86_64||Apr 26 2016||1.9.8||Yes||Yes||Gold||Philipglo Joshua Opulencia|
|Show||Debian GNU/Linux 8.x "Jessie" x86_64||Apr 12 2016||1.9.7||N/A||Yes||Platinum||firencombomaster|
|Show||Arch Linux x86_64||Dec 29 2015||1.9.0||Yes||Yes||Platinum||an anonymous user|
|Show||Arch Linux x86_64||Dec 06 2015||1.8-rc3||N/A||Yes||Silver||Mike Swanson|
|Show||Debian GNU/Linux 9.x "Stretch" x86_64||Dec 20 2015||1.8-rc2||Yes||Yes||Bronze||an anonymous user|