Alex Mauer isn't as upbeat as a lot of other chiptune artists are. His stuff is usually pretty calm and actually sounds like a game soundtrack. Dead Mother Goose and Antarctica, while incredibly short, are both very good.
The Prize Fighter Inferno, Claudio Sanchez's solo project, is the greatest mix of folk and electronica I've ever heard. I've checked out other artists labelled under "folktronica" but Claudio just really captured something great here. Catchy melodies are everywhere on this album.
I know you said "no metal," but Russian Circles is great whenever I'm working or studying. Station or Enter should be your first purchase. Its post-metal, so there are no vocals, but the music is very grand, heavy, but still has some subtlety to it.
I second Ravenheart's Sarah Fimm recommendation.
And lastly, Vanden Plas is a band of unfiltered genius and you should listen to everything they touch.
EDIT: TheMadgician, what do you think of The Protomen? They have original albums that are Mega Man concept albums as well, and I think they precede the Megas by some time.