"This title is an action-adventure game with new, exclusive content and features created only for the WiiWare version," reads the relevant chunk of a Nintendo press release.

Bearing a mild resemblance to Nintendo's Metroid series, Cave Story follows hero Quote as he awakens deep in a cave with no memory of how he got there. The game has garnered worldwide praise as well as ports for Mac OS, Linux, other operating systems, and homebrew ports for the PlayStation Portable and Nintendo DS.

A release date or price--presumably not free, in a break with tradition--for the downloadable game is as yet unknown.