Summer of Arcade promotion on the Microsoft Store. Those who pick up a copy of Bastion via the Microsoft Store will also receive a free copy of Twisted Pixel's adorable adventure, The Maw. As we mentioned only a few words ago, The Maw is positively adorable and a decent game to boot, making this an attractive deal for those interested in Bastion.
Strangely, the site notes that the deal applies to "any" Summer of Arcade purchase, though a footnote claims that the deal is valid solely for Bastion. Considering Bastion is currently the only Summer of Arcade title available, it's possible that the deal will be applied to the rest of the Summer of Arcade lineup as each title is released.