I had the same issue but with High Sierra on a 2014 15" Macbook Pro. After about 20 minutes of trying to figure out what "-force-metal" is and how to implement it, I actually got this very beautiful, well-designed, charming game up and running but I figured I'd pop in here to get a little more specific about using Terminal to launch the game in case it might save any other turbo n00bs some time:
If you've never used Terminal, it's Mac OS's built-in, ridiculously powerful command-line tool that can do everything from launch (and modify) complex programs to basic tasks like securely and immediately empty files immediately without sending them to the trash.
Launch Terminal like a normal app (it'll be in the Utilities sub-folder of your Applications folder, or just launch it from Spotlight search and save yourself a couple of seconds). One cool thing about Terminal that not every tutorial page I've come across tends to let you know is that you can skip being too anal about typing in the command line altogether when opening programs/apps by just drag-and-dropping the whatever-it-is into the Terminal window directly and treating it like a basic launcher of sorts. The filepath necessary for launching the app will appear automatically, properly formatted. For example, (and to cut to the chase a little,) here's the command I eventually discovered that I need to use to launch A Short Hike successfully on my system (it will look different on yours, bear with me:
open -a /Users/Prizmatics/Video\ Games/AShortHike.app --args -force-metal
So, I type in "open -a", press spacebar, drag the A Short Hike icon from it's folder into the Terminal window after open -a, loading the necessary filepath, and then I type in the "--args -force-metal" business (this is what took me a while to stumble upon) and press Return. Ta-daahh! Game time!