Super Indie Kart, the 16-bit kart racer that features a wide range of characters from indie games, will include a Runbow level. The Australian developer One Legged Seagull has posted the trailer on their Youtube channel, which I've posted below.

Judging from the trailer, it will take Rainbow Road a run for its money.  You can follow the developer on Twitter, but also make sure to follow 13AM Games!