It should be working fine now, at least it's working over here (2014 mac mini, El Capitan).
Maybe it's just me. What are the minimum requirements to run the program? I downloaded and tried both Mac versions but once I unzip the file and click to start the application, it just never goes.
Direct 3D 9 compatible graphics would be the only minimum requirement holding it back. One thing I have been noticing in El Capitan is that you have to open it a few times before it actually responds and opens- I have no idea why that is the case. Try alt-mouse > open a few times, and it should eventually start. Sometimes it takes a little while to start when you first run it.