GTA V

Testers needed: GTA V on Linux is... fun. These workarounds will probably constantly change, and the only way to verify them is to try them out! So please do so if you have the time

Note: A guide with more focus on the Heroic Games Launcher is available here

GTA V requires the use of GloriousEggroll's version of Wine (download and extract to anywhere, you'll need it later) instead of the default Wine/Lutris Wine. Installing DXVK (also download and extract) is also very much recommended, as otherwise the game will, frankly, run and look like dogshit.

To start, create your Wineprefix directory (any directory, anywhere, just gotta know where it is) and open up a Terminal inside it. Run export WINEPREFIX=$PWD to set your Wine prefix to the current directory, then run /path/to/wine-ge-6.14-x86_64/bin/wineboot -i && /path/to/wine-ge-6.14-x86_64/bin/wineserver --wait to initialize the Prefix & wait for init to finish. Next, open up your Legendary config file (by default at /home/$USER/.config/legendary/config.ini). Add the following (replacing the paths to Wine-GE and your prefix location):

[9d2d0eb64d5c44529cece33fe2a46482]
wine_executable = /path/to/wine-ge-6.14-x86_64/bin/wine64

[9d2d0eb64d5c44529cece33fe2a46482.env]
WINEPREFIX = /path/to/prefix

In the same Terminal you ran the export WINEPREFIX=$PWD command in, now run /path/to/dxvk-1.9/setup_dxvk.sh install to install DXVK into that Wineprefix (again replacing the path with your own).

And now, you can actually launch the game (run legendary launch 9d2d0eb64d5c44529cece33fe2a46482 now). A Rockstar Games Launcher install window will pop up, please select your desired language there and click continue a few times after that.

Important: When using a Wine-GE version above 6.21 (7.x), the first time you run the installer, it'll freeze and eat up your RAM until either your PC or just it crashes. When you're on the "Preparing to install" screen, kill the launcher installer (On KDE, you can press Ctrl + Alt + Esc & then click the window to kill it, not sure if a similar combination exists for other DEs).
After you close it, the "original" installer will continue installing DirectX and VCruntime. Once that's done, you'll get the same "Unable to launch game, please verify your game data" message. Click OK there, then launch the game again. This time the Launcher will install with no issues.

You should now be on a login screen. Log in to your Rockstar Account, say no to the "Scanning for already installed games" message and close the launcher once you're on the game list (since it'll not detect that the game is on your account the first time it's launched). Then, launch the game one more time and it should just start.