Super Mario Spikers
Next Level Games developed two fun soccer games, Super Mario Strikers, then a bunch of other junk before the excellent Luigi’s Mansion: Dark Moon. Somewhere after the Wii version of Strikers, though, it was working on some unholy blend of volleyball and wrestling. The one without cowboy hatted announcers and steel chairs.
Mario Volleyball turned into Super Mario Spikers. According to Unseen 64, it made it to a playable prototype phase, which is what scared Nintendo off because of the level of violence.