The Steam Alpha build is actually DRM-free. It downloads through Steam of course but you don’t need to be running Steam to run the game. In this case Steam serves purely as a download and auto-patching mechanism, not as a DRM solution. (We have actually used Steam in this way for a number of our games.)

There are other possible futures, including one in which we start implementing aspects of Steamworks like cloud saves and other requested features, in which case Steam would become a more intrinsic part of the game. I can also imagine a future in which we released a version that downloads directly through Humble! We can’t promise either of these futures 100%, because then we will look like fools if they do not come to pass.

But know that the Alpha 1 build is only using Steam as a download tool, just like a Humble Bundle download would.