I have been using Steam for about a year for game to use on our iMac, I really love it. It has a great chose of games at LOW prices. It also had this great option for “early access” for games that are still in development stage but you can still play and help to iron out bugs, once the game is complete you will have the full version for a fraction of the price. Have a look for yourself.
There is a wide range of games for most platforms. e.g Windows, Mac and Linux.
- Steam’s summer sale is great for Mac gamers (reviews.cnet.com)