At a glance
Frozen Synapse has a Mac version: Steam sells it for macOS. The Mac requirements list only Intel: on Apple Silicon Rosetta 2 runs it, and old Mac versions sometimes do not start on current macOS. Try it in Steam for Mac first.
Frozen Synapse came out on Steam on 26 May 2011, made by Mode 7.
What your Mac needs
The Mac requirements list only Intel.
Minimum macOS in the Steam requirements: 10.5.8.
Steam requirements list at least 0.512 GB of memory for Frozen Synapse.
Allow about 0.22 GB of disk space for the Mac version.
How to play
Open Steam for Mac and install Frozen Synapse as usual.
If the Mac version will not start, you can install the Windows version through Uncork: download Uncork, sign in to Steam and install Frozen Synapse from there (0.22 GB). We have not tested it ourselves.
The Windows version through Uncork needs a Mac with Apple Silicon (M1 or newer).