Steam has finally landed for users and to celebrate, are giving away for free.

Portal is one of the first group of titles to be sold with the SteamPlay function that allows those buyers to play titles on both their Macs and PCs.

Over 50 titles have launched on the Mac service and all of them launch with the SteamPlay functionality.

The launch titles include Braid, Peggle, Machinarium and classic point and click titles like Loom and Indiana Jones and the Fate of Atlantis.

Thanks ThatVideoGamesBlog.

By Ewan Aiton