This is the C3 Demo of SM64: Year of the Plumber, a hack made by DobieMeltfire that was never finished, it contains 16 Stars and 2 Main Courses. The project would later be rebranded into Somari 64.
This port has now been uploaded to the site for archival purposes and better accessibility. Do note that it is possible some of the death barriers may not be present, so if you get stuck in a pit, press "exit course" and you should be good.
(Some Images were taken from the SM64 Hacks Wiki)