Oh, sorry. No, I'm pretty sure it's not, unless the game says "Steam" under DRM (mostly Steam exclusives). It's a separate vendor entirely, but I tend to prefer them to Steam since you don't need to install any of their software or stuff, and you can keep the install files even after you're done with them to back up or such. No game achievements, though, beyond that really weird achievement system they recently put in for how many games you buy and what online store features you use.
No shill, no shill.