not every game has a mac build, so i really appreciate those that do, especially since it's not a requirement! but i've been manually changing permissions for a couple of unity games that the system stopped me from opening. i'm not sure why this happens -- i'm not exactly an expert -- but i came across a great post that has been written and discussed in detail.

https://ldjam.com/events/ludum-dare/47/the-looper-encounter/important-note-for-mac-builds

this above post is probably going to be useful not only for unity devs porting their games to mac, but also mac users that have trouble opening mac builds.