Fixed issues with the working directory of the Launcher and Game. Linux usually sets the working directory to the user home instead of the directory where the actual program was run from.
The fix unfortunately won't work by itself, you should delete the open-ig-launcher.jar, open-ig-launcher-config.xml and open-ig-update.xml from the home directory. Then, go to the install directory via the Terminal and run the Launcher:
java -jar open-ig-launcher.jar
Chose the Update Launcher button or Other > Repair Launcher option from the menu.
Related issues: Issue #682, Issue #694