Actually, some of those drawings
were for a real game project
according to this thread, a gamemaker game that Kenneth Fejer (a guy's name) was apparently working on and probably discontinued. So it wasn't all just to strut his portfolio, but actually for a purpose at one point. I'm guessing most of those materials that don't use copyrighted material are also from other game project he has worked on.
But I totally agree that his artwork is awesome and inspiring. Apparently he's worked on a quite a few
awesome projects, including Contra 4 for the DS.
I'll revisit this later with other good mockups and screens. I sort of wrote this in a hurry, just figured I should correct a few things.