The first 10 games are due to be released on Steam thanks to Steam Greenlight, of which 50% are to be Mac-compatible.
Steam Greenlight is a platform that enlists the help of Steam’s community in deciding the next wave of games to be released on Steam. Greenlight allows developers and publishers to post media about their games in order to convince the community that their game deserves to be released on Steam.
The service was launched on August 30th and has very quickly had hundreds of submissions. There are currently 345 Mac compatible submissions on the Greenlight that you can browse freely here. Support projects that you are interested in, voting on a game does not obligate you to purchase it if it reaches steam.
Below are a list of the first 10 games to get the greenlight with the Mac compatible games marked appropriately.