I hypothesize rejection on one single factor; XSeed has yet to release any Steam-only games on the Humble Store. Their catalog there is completely DRM-Free.
Fair point. I just noticed Bullet Witch is DRM-free on humble. Was that rejected here? I remember asking Xseed about it and all i got in reply was "no current plans".
I guess we will have to wait and see how this plays out....
Or it might be coming to GOG and it just hasn't been announced yet.
The launch trailer features the steam and humble logos only. Unless something happens behind the scenes in the pre-release window (May 29 is launch day), i wouldn't hold my breath.