Another Castle is the work of developer Uncade, the company name of lone wolf developer David Byers, and takes place in a series of randomly generated side-scrolling levels in which you look for an item which is, inevitably, not there – a reference to the elusive Princess Peach. When you finish the game, the item is unlocked and actually attainable in future playthroughs.
Byers submitted a prototype to Nintendo and got approved as an eShop developer, suggesting that Nintendo is loosening its restrictions on things like developer size. Another Castle is planned for release on PC, Mac, Linux, iOS, Android, and Ouya in addition to Wii U. It's being supported by a Kickstarter, with a tiny $12,000 goal. A playable prototype can be found on the official site.