In the meantime, I've tried to install and run Sunbeam on another machine with a newer nVidia card and drivers and two different linux distros, Kubuntu 17.10 and KDE Neon. On both, the game crashes on launch. I sent feedback on both. I do have a laptop with an i5 and integrated intel graphics, also running Kubuntu 17.10. I'll give it a try on that and see how it goes.
Out of interest, have you tried running any other Unity games on those machines? Do you have similar problems, or is it just with Sunbeam? I'm wondering if it could be the particular version of Unity I used or if it's a general problem. I could try rebuilding the game in a different version of Unity to see if that makes a difference. I was planning on issuing an update at some point anyway, so I'll bring that forward if we can't find any other solution.