There are actually quite a few good platformers on Microsoft's XBLIG platform, like Magnetic By Nature or Apple Jack 2 to name a couple. Based on its trailer, we might be able to add IOTA to the list.

IOTA is being developed by a team called The Cashie Brothers, who are, in fact, actually brothers. They set out to finish a project, and IOTA was the result. It's a color-switching platformer like Outland or Polara where you can switch between two different colors. You can absorb like-colored projectiles, which will fill an energy meter. This can then be used to dash or hover. The game becomes a balancing act between energy absorption and the use of the two abilities that drain what you've gathered.

The Cashie Brothers said the game should last around three to five hours, depending on player skill. They also said that despite the cutesy look, the game will be relatively challenging. Expect it "within the month" for $1 on XBLIG.