Super Donkey

Super Donkey is an unreleased platformer starring an unnamed proto-Rayman-like aviator/explorer who resembles the main character of Nintendo's earlier game Sky Skipper. Two builds were found, though neither one has any sound or music and the onscreen timer is non-functional in both. Judging by the name and some unused sprites, this might have been a Donkey Kong-related project.
Various elements of Super Donkey would eventually be used in Super Mario World 2: Yoshi's Island.