The ridiculously good Bit.Trip Runner has a sequel, of sorts, on the way. It's not part of the Bit.Trip series, though, so it's simply called Runner 2. Which about sums up what's going on.
Note that, as good as this already looks, it's a "super sneaky peek" at pre-alpha code, which you'll eventually realise with the lack of effects or background animations.
Trailer: Runner 2 Pre-Alpha Footage (Gaijin Games) [IndieGames]