a few weeks ago (but rated by the ESRB back in January), the PC version of Insanely Twisted Shadow Planet is available now on Steam. The Del Taco-promoted game includes support for the keyboard and mouse set, alongside free "Shadow Hunters" DLC.
Insanely Twisted Shadow Planet was one of the highlights of last year's "Summer of Arcade" for XBLA. We said it's "a world that begs to be explored" in our review. So ... go explore it for $15, if you don't want to wait until the inevitable Steam sale makes it less than a mochaccino.