|title=Sonic the Hedgehog 4 Episode I (WiiWare JP prototype)
Sonic the Hedgehog 4 Episode I (WiiWare JP prototype) is an early version of Sonic the Hedgehog 4 Episode I which was accidentally released on the Japanese version of the WiiWare service on the release date. It contains many differences from the final game and includes different level designs and music changes. It shares a strong resemblence to the PartnerNet build, which in turn, also resembles the iOS version, although it is a much later build. It was built on February 9th, 2010.
Act 2 contained the controversial Mine Cart level where Sonic remained in the cart throughout the level, which controlled poorly. It is controlled using the Wiimote's tilt function. The Mine Cart section is reduced greatly and plays automatically in the console version.
The moving wall in Act 3 was much faster and harder to complete the area compared to the final version.