I'll put short guide here what I did, because I had help from some guy on #playonlinux irc channel and he helped me a lot with setup, so I'm not sure do I remember everything correctly.
1. I updated winetricks - https://github.com/Winetricks/winetricks
(I think this step is not relevant, since Lutris uses it's own version)
2. Installed latest version of Lutris for my distribution - in this case 0.4.13
3. In Lutris - I have downloaded staging-2.16 (it's kinda strange way to do it: in Lutris application menu click -> Lutris -> Manage runners -> find Wine (not Wine Steam) -> click Manage versions -> there you have list with checkboxes - it behaves strange there, because checkboxes are not relevant, you just have to click once on it and wait -> and download will start.
--> now we have all pre-requirements - and it's time to create wine prefix.
4. Open Lutris -> click "+", to create new game
4.1. Game info Tab
4.1.1. Name - write some name for Game (Steam, SteamDOS2, whatever.)
4.1.2. Runner - select to be Wine (not Steam, not Wine Steam, just Wine) - It's written: Wine (Runs Windows games)
4.2. Game options Tab
4.2.1. Executable - select any dummy file that can't be executed, like txt, pdf, whatever (it's important for some steps later)
4.2.2. Wine prefix - set directory name, has to be full path, fe.: /home/mtodor/lutris-steam64
4.2.3. Prefix architecture - 64-bit (this is important, I don't think so, that DOS2 works on 32-bit platform)
4.3. Runner options Tab
4.3.1. Wine version - staging-2.16-x86_64
-> everything else default
4.x click Save to finish creation of Lutris Game (if game doesn't appear, close Lutris and open)
5. Run created Lutris Game - it should fail (since not executable file is used), but correct wine prefix folder should be created
5.1. (optional) double check if version of wine prefix is correct: go in wine prefix directory (fe.: /home/mtodor/lutris-steam64), and "less system.reg", you should see: #arch=win64
6. Right click on game icon in Lutris and select Winetricks
7. Select - Install an application -> click OK, then click Cancel on next dialog
8. then you should get new dialog with option - Install a Windows DLL or component, select that and click OK
9. on next dialog select dotnet40 -> click OK (that will finish with some error, what you can ignore)
10. again, Right click on game icon in Lutris and select Winetricks
11. Select - Install an application -> click OK
12. on next dialog find Steam and select it, click OK to install, it will finish installation
13. Right click on game icon in Lutris and select Configure
14. go to Game options tab and set Steam as Executable - fe. /home/mtodor/lutris-steam64/drive_c/Program Files (x86)/Steam/Steam.exe
15. In Arguments add: -no-cef-sandbox (that should help Steam to work properly in wine)
Next step is to run Lutris Game, that should open Steam and you should install DOS2.
If you already have installation, you can just start installation in new Steam (so that it start downloading) and then turn Steam off, copy manually "steamapps" from previous installation to new "steamapps" location.
After installation is finished start Steam and start DOS2 from Steam -> it should install some dependencies and fail, after that you can do following.
1. Right click on game icon in Lutris and select - Run EXE inside wine prefix
2. Navigate to "EoCApp.exe" - fe. /home/mtodor/lutris-steam64/drive_c/Program Files (x86)/Steam/steamapps/common/Divinity Original Sin 2/bin/EoCApp.exe
3. And execute it, game should run!
If that doesn't work, you can try following:
- install latest version of Mono that wine prefix (download from http://www.mono-project.com/download/#download-win
64-bit version) and same as I have explained before, select "Run EXE inside wine prefix" and run that installable
- install additional libraries over winetricks - fe. d3dx10, d3dx10_43, d3dx11_43, directx9, vcrun2015
=> problem is that I have tried a lot of things before I tried to run DOS2 directly, that's why I'm not sure, are some parts relevant or not.
I hope so I didn't miss anything and that this guide will be helpful for you.
P.S. for some reason I can't edit first post.