Valve has made good on its promise and unleashed its digital distribution service, Steam, on Apple’s range of Mac computers running Mac OS X.

This will give Mac users access to an initial selection of 57 games to download and play through the service (all listed below), while new games will be added to the roster every Wednesday.

These games will all feature Valve’s ‘Steam Play’ functionality, which enables gamers to purchase one copy of the game via Steam, and then play the game on a computer imbued with the power of Windows or Mac OS, all through a single Steam account. It’s the Valve way.

Also, Valve is giving away the excellent, multi award-winning first-person puzzler, Portal, for free!

If you’ve got a Steam account, you’re now able to log in and download the brilliant game at no cost to yourself. This offer ends on May 24th, however, so if you’ve ever wondered what all the fuss is about, now’s the perfect time to get Portal. You’ve got no excuse!

Here’s the list of games now available through Steam for Mac users:

• And Yet It Moves
• Atlantis Sky Patrol
• Bejeweled 2 Deluxe
• Bob Came in Pieces
• Bookworm Deluxe
• Braid
• Brainpipe
• Chocolatier: Decadence by Design
• Chuzzle Deluxe
• City of Heroes: Architect Edition
• Civilization IV: The Complete Edition
• Cooking Dash
• Diaper Dash
• The Dig
• Diner Dash: Hometown Hero
• DinerTown Detective Agency
• DinerTown Tycoon
• Dream Chronicles: The Chosen Child
• Escape Rosecliff Island
• Fairway Solitaire
• Fitness Dash
• Football Manager 10
• Galcon Fusion
• Gemini Lost
• Guns of Icarus
• Hotel Dash Suite Success
• Indiana Jones and the Fate of Atlantis
• Indiana Jones and the Last Crusade
• KrissX
• Loom
• Luxor
• Luxor 3
• Luxor: Mahjong
• Machinarium
• Mahjong Roadshow
• Max and the Magic Marker
• My Tribe
• The Nightshift Code
• Nightshift Legacy: The Jaguar’s Eye
• Parking Dash
• Peggle Deluxe
• Peggle Nights
• Portal
• Professor Fizzwizzle and the Molten Mystery
• Quantz
• Sam & Max: The Devil’s Playhouse
• Tales of Monkey Island Season 1
• Toki Tori
• Torchlight
• Trijinx: A Kristine Kross Mystery
• Unwell Mel
• Valarie Porter and the Scarlett Scandal
• Wandering Willows
• Wedding Dash 2: Rings Around the World
• World of Goo
• Zenerchi
• Zuma Deluxe