There are four controller ports, two USB ports for memory card slots, and output is composite through a 3.5mm jack. It’s a great piece of work and looks exactly like a miniaturized GameCube.

Nintendo released its own Wii Mini toward the end of the Wii's life in 2012, but it came with significant compromises: no online connectivity, no GameCube controller ports or game compatibility ...

The controller sold for 74,000 yen ($663 USD) and came paired with an early Nunchuk prototype and a longer and slightly different looking sensor bar that plugged directly into the memory card slot.

What’s especially great about this hack is that the Wii input card is completely self-contained, and even includes four ports on the back for connecting wired GameCube controllers.

Yahoo Auctions This controller comes with a sensor bar, meant to plug into a GameCube's memory-card port. This image includes the final Wii sensor bar for comparison's sake.

Although it works with full-size original GameCube controllers, either with a 3.5mm or USB adapter, Madmorda also recently produced a fully functioning mini GameCube pad.

A prototype Wii Remote for the Nintendo GameCube showed up over the weekend at an auction in Japan on Yahoo Auctions, alongside an accompanying Nunchuck controller.