The Pyre reveal last month only mentioned a PlayStation 4 version of Supergiant's upcoming action/RPG, but they are discussing a Windows edition of the game at PAX East, and sure enough this post from a couple of days ago mentions a simultaneous Steam release (a Steam listing for the game is now online, though this is basically a stub at this time). That post includes a reveal trailer, and now Polygon has a 20-minute video from PAX East showing the game in action, and there are previews on a bunch of sites including GameSpot, IGN, and Kotaku. Here's an overview:

From the team that created Bastion and Transistor, Pyre is a party-based RPG in which you lead a band of exiles to freedom through an ancient competition spread across a vast, mystical purgatory. Follow the stars as they guide you toward a series of celestial landmarks, then guide your fellow exiles to glory through action-packed, tactical confrontations against adversaries whose own freedom is at stake.