Wii U hackers have modified various aspects of Mario Kart 8 and the system itself using an exploit of the console's browser.
YouTube user MrBean35000vr published a video demonstrating a series of minor adjustments to the game on Saturday. These tweaks include making the music on Moo Moo Meadows run faster than intended and renaming courses.
According to the video's description, the hackers used "on-the-fly RAM edits" carried out via a recent browser exploit.
"All of this may not look impressive, but it's merely because we don't even know where to start; we can do anything now, anything at all!" the hacker wrote. "Custom tracks, custom songs, you name it. We just have to decipher the RAM and work out how."
MrBean35000vrr previously contributed to CTGP Revolution, a Mario Kart Wii mod which added 216 custom tracks to the game complete with online play against other mod users.
The hackers say they have no plans to publicly release their work and will not let it be used for cheating. Instead, they hope the exploits will allow them to create game-extending mods.
Nintendo said in June that Mario Kart 8 has sold two million copies worldwide.