Also on Steam is a playable demo for Magic 2015 - Duels of the Planeswalkers, the just-released new installment in the card-based strategy series (thanks Frans). Here's word on the magic:

Hunt bigger game on a bold new adventure with Magic 2015—Duels of the Planeswalkers! Command powerful creatures and wield devastating spells to defeat your opponents in this epic game of strategy.

Hone your skills as you battle your way across the planes of the Multiverse. Beware though, Planeswalker. Your biggest danger lies ahead. Garruk Wildspeaker, the greatest hunter known, has fallen under the curse of the Chain Veil. He now mercilessly stalks his own kind. Find him and stop him ... before he finds you!