Hi Thomas,
It was overdue anyway. I checked the game in Ubuntu (17.10).
How to Install:
#1: Download the Linux version. (Usually you should need the 64-Bit version.)
#2: Unzip/Extract the Archive to a folder of your choice (in Ubuntu this is done with the Archive Manager)
(I just unzipped the game file to the downloads folder)
#3: Set the Executable flag of the extracted file (NarrowBoatSim_LinuxX11). In Ubuntu you can right click the file in the file manager and select "Properties", then "Permissions" then check "Execute". Then close the Properties Window again.
#4: Execute the game. (In Ubuntu: Just doubleclick the game file in the File Manager)
If all worked well, the game should now start & work. The graphics driver/card has to support at least Open GL 2. But most PCs of the last 5-10 years should support this.
Just in case you want to know:
Configuration and game progress is saved in a special user folder (if the game ran at least once):
~/.godot/app_userdata/Narrowboat_Simulator
So you can move or delete the executable file without losing game progress.
Michael