There seems to be a lot of confusion about how to run games built on the Unity engine distributed by Steam on a Linux system. I recently solved this problem after backing the promising survival sandbox game Planet Nomads on Kickstarter. Here is how to configure an Ubuntu Linux system and launch Planet Nomads successfully.

Prerequisites

If you have an Nvidia card, you must download and install the official proprietary drivers provided by Nvidia. I could not get Unity to launch with the open-source drivers. Once I installed the proprietary (closed source) drivers, I was able to launch Planet Nomads from the Steam application.