I don't particularly want to admit that Natsume's Gabrielle's Ghostly Groove 3D is my favorite game on the 3DS, but when I play a game every chance I can get for two weeks straight I feel I should mention it. Be gentle.
What can I say, I'm a sucker for handheld rhythm games. Blame Elite Beat Agents if you must blame anything. I'd been meaning to check out the WiiWare version, Gabrielle's Ghostly Groove: Monster Mix, so when I saw this on the shelf at my local Games N' Stuff (not a real store) I had to grab it.