It looks like there is a Steam configuration issue with the game. We are working on it and it should be fixed soon.
In the meantime, if you can't launch the game directly from Steam you should be able to launch it directly from the game folder.
If you are not sure where it is, you can do find it by right-clicking on the game in your Steam library, selecting Properties and then Local Files and then click Browse Local Files.
The game folder will open and you can launch the game by double-clicking PlanetaryProspectorsARM.exe
This should be fixed shortly regardless and please let us know any other issues you have.
Thank you and sorry for the trouble!