When Mario Kart made its way to the DS, Nintendo included a mission mode. Nearly ten years after its release, someone has discovered an unfinished mission mode in Mario Kart Wii.
User MrBean35000vr has uploaded a video to YouTube showing off a range of missions hidden within Mario Kart's Wii release. The menus for the mission modes don't actually have any text, and you can't get them to display correctly without simulating some data that the game draws certain mission parameters for.
The file with those parameters, however, appears to have been removed from Mario Kart Wii's release. So MrBean35000vr made his own version, and went through the painstaking process of hacking everything together to get the missions to work.
Some of the missions range from throwing red shells at Goombas to earn points, drifting a certain amount of times within a time limit, completing laps within a certain time, gathering a certain number of coins, and ramming a spinning top off a stage.
Because Mario Kart Wii wasn't, well, a PC game, it makes more sense as to why these missions took so long to be discovered. Data mining is a lot easier when you have access to all the files, or can easily unpack them, and that wasn't the case when Mario Kart first launched on the Wii. On top of that, reverse engineering isn't the easiest process.
Nonetheless, it's interesting to see that Nintendo obviously had this in mind. It makes one wonder what other mysteries are lurking in other Wii, Wii U and Switch games.