liamdawe:
There is a problem in gtklauncher on amd64 systems at the moment. You may try to execute it by hands:
locate OpenRA.Game.exe (it gives the path were the game was installed)
cd /usr/share/openra/ (or to the path given above)
mono OpenRA.Game.exe Game.Mods=ra Graphics.Renderer=Gl (this is an execution it by hands)