Still Life for Mac was working on MacOS Sierra 10.12, but stopped working after upgrade to MacOS Mojave 10.14.1. Removing and reinstalling the game didn't help.

I'm having this same problem... I didn't read the fine print about what OS it would work for, but I've yet to get it to work at all. I was really excited to get to play this game.

Same problem.
I contacted the support and this was the answer:

"Please try changing the version of Wineskin and Wine engine. To do this you will need to install Wineskin Winery from here:
http://wineskin.urgesoftware.com/tiki-index.php?page=Downloads
Start the application and use it to download additional versions of Wine (by clicking +).
Now you should be able to right click the game's app, select Show Package Contents and run Wineskin.app.
If the Wineskin.app is not there go to Contents > Resources > game, right-click the game's app select Show Package Contents and open Wineskin.app.
In the Advanced options change the engine to the one you have downloaded."

For me it worked. I hope this helps you.