Nintendo's secretive EAD development team developed around 30 Wii U game concepts using a monitor taped to two Wii Remotes.

This was the second of the company's early GamePad prototypes. The first was a Wii Zapper with an LCD screen mounted on the front.

Both creations were discussed in a new Iwata Asks interview discussing the creation of pack-in game Nintendo Land.

"We used this prototype and two Wii consoles to run simulations for Wii U," EAD boss Katsuya Eguchi said. "EAD isn't a hardware department, but a 'handicraft team' knowledgeable about hardware makes stuff like this.

"One of the staff members expressed a desire for a game that would gather Nintendo's franchises into a single spot and each franchise would have something to do with the others. It was quite a grand concept. But we were like, 'How do we bring them all together?' We didn't take it too seriously."

The Wii U is due to launch in Japan this weekend. Nintendo shifted 425,000 consoles during the system's US launch week, the company announced today.