Works fine using Yosemite. From memory I think I had to download and update the game manually but, after that, no problems that I've found.
I'm using a 2010 17 inch MacBook Pro. Later machines might have issues, so check first, if possible.
There's a lot of gameplay to The Sims Medieval. Plus it's a lot of fun. Similar but different to other Sims games so, if you're into The Sims, then you should like this one.