Starting with XIII on October 9
The official site gave it away, to some extent, but here we go: Final Fantasy XIII is coming to Steam on October 9, priced at $15.99, with XIII-2 and Lightning Returns arriving for PC by spring 2015.
XIII already has a listing on Steam and is open for pre-purchase — doing so will save you ten percent, bumping the price down to $14.39. Not bad. System requirements are up, too.