With PC games continuously losing retail shelf space and Mac games having little shelf space to begin with, Steam presents the first significant distribution platform, digital or otherwise, the Mac gaming platform has seen in years (ever?). It remains to be seen if Steam for Mac and Steamworks – the platform's suite of tools covering everything from copy protection, anti-cheat support, and key-based authentication to Steam community, Steam Cloud, and microtransactions – will be enough to encourage publishers to incur the added expense of porting games to the Mac OS X platform but tomorrow's launch offerings are certainly promising.
Valve says that, in addition to the games launching tomorrow, on "subsequent Wednesdays, additional collections of Mac titles will become available, each designed to highlight specific functionalities of Steam on the Mac." The first collection will highlight "Steam Play," meaning games that work on all "Steam supported platforms," currently Windows and Mac OS. Valve identified its own Portal and the Diablo-esque Torchlight as launch titles, the only two to be officially announced.
The Steam for Mac beta client reveals over three dozen "Mac games," all currently available via Steam on Windows. Notable entries include LucasArts classics like The Dig, Indiana Jones and the Fate of Atlantis, and Loom, some of Telltale's episodic offerings, including the most recent installment of Sam & Max and the entire first season of Tales of Monkey Island, and several PopCap titles, like Peggle Deluxe, Peggle Nights, and Bejeweled 2. Also listed and currently playable (unlike every other listing in the Mac beta, short of Portal) is Team Fortress 2, though it's curiously not mentioned in Valve's press release which heralds Portal as "the first of Valve's Source engine based games available on the Mac."
Notably still missing from this list are Valve's Half-Life and Left 4 Dead series, PopCap's already-Mac-compatible Plants vs. Zombies, and plenty of other Mac-compatible titles currently on Steam. This forum thread has a nice list of potential Steam Mac games, and we've asked Valve to comment on how many of the currently listed games will be available tomorrow. Check out of a screenshot of the Mac store, as it looks today in its beta state, after the break.