The time-shifting platforming adventure is now available to digitally download for Windows PCs via Greenhouse, Impulse and Gamersgate, all for the low price of $14.95. Where it's not available yet, unfortunately, is through Valve's Steam service. That version has been pushed back until tomorrow meaning Steam Achievements will just have to wait.
Did I mention that we really, really liked Braid? You should get it. There's a demo version available, should you find our recommendations untrustworthy.