I have no recent Linux experience.
I have installed v120.0.1 on a PC with a fresh installation of Mint, so no earlier versions of Simutrans have been installed previously.
When I double-click the program icon v120.0.1 opens and runs as it should. However, when I open a Terminal window in the v120.0.1 folder and enter simutrans v111.3.1 opens instead.
The purpose of this installation is to run an online server. I need either to be able to run v120.0.1 from the Terminal or I need to know how to add commands when executing by double-clicking the program icon (I know how to do this in Windows but not Linux).
When typing simutrans on Linux, it locates an executable called simutrans on the path. The current directory is not on the path. You appear to have two versions of Simutrans installed, where 111.3.1 is either the only one installed properly, or is installed so that it is found first. If you type ./simutrans, it will run the program located in the current directory.
Ah, perfect. Resolved. Thank you.