This FAQ is intended for those of us who run an unsupported (in GOG terms) Linux distribution, for as of today it seems like there's not much help if you encounter a problem with your Linux game on an unsupported distribution.


If you know of a bug and a workaround. Please submit to this thread. Also, list some of the games affected by the bug.
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My game does not start..
First of all, when a game does not start in Linux. Start it from the terminal. This way you get precious log statements from the running application.

How to start a game from the terminal
1. A terminal starts in your home directory by default.
2. If you've installed a game using the GOG installer, and installed it to the default directory, it should have been installed to the following directory:

$ cd "/home/<user>/GOG Games/<game name>/"

3. After you've navigated to the game directory (the command above), type the following command ($ represents user mode, and is not part of the command)

$ ./start.sh

4. Now, you should get some error messages in your terminal, if the game does not start.

System.Exception: Magic number is wrong: 542
When the this message; "System.Exception: Magic number is wrong: 542", is displayed, you are using a version of Mono (Linux runtime for the .NET framework) with a known bug.

The bug is reported on the official Mono GitHub page (https://github.com/mono/mono/issues/6752#issuecomment-365212655) and is fixed by adding the following environment variable: TERM=xterm.

To successfully run your game, run the following command from the terminal.

$ TERM=xterm "./GOG Games/<game>/start.sh"

Try it, to see if it fixes your problem.

For a more long term solution, you can edit the start.sh script or edit the EXEC-field in the desktop shortcut.
The exec field should look like this:

EXEC=env TERM=xterm "./GOG Games/<game>/start.sh"

The following games are known to be affected by this bug:
* Apotheon
* Escape Goat
* Hacknet

Might also find some tips and tricks in the Official gOg Linux threads (both stickified):

https://www.gog.com/forum/general/general_linux_faq_and_troubleshooting/page1

https://www.gog.com/forum/general/linuxvangog_fantastic_linux_mac_guy_and_where_to_find_him/page1

Holy shit, dude! I just encountered this bug for the first time yesterday with Mercenary Kings and it didn't occur to me to search the magic number part of the error. This thread of yours has been a real godsend for me, thanks! :)