I spoke to Dewy's Adventure producer Shingo Mukaitoge, who also produced Elebits, and he's a cool guy. Dewy's Adventure might be described, in a very general and not entirely accurate sense, as Loco Roco in 3D. You hold the controller horizontally, like an NES pad, and tilt the world, and Dewy slides around it. You can't move Dewy directly, but you can make him jump and attack enemies. Get to the end of each stage. Straightforward.
Pressing up and down on the D-pad alters Dewy's temperature. Dewy is a droplet of water, see. Press up and he becomes a floating cloud, able to zap enemies with lightning . Press down and he becomes a block of ice, able to do, uh, something cold. This works with tilting the world in this sort of manner: if there's a body of water, you can jump in it, tilt the world so the water deforms, then turn it to ice. When you tilt the world back, the ice stays that way.