Sethbling has made a video demonstrating a new discovery by p4plus2, who has written the code. Sethbling and others can exploit some glitches of Super Mario World to inject p4plus2’s Flappy Bird code into unused portions of the game’s memory. It turns Super Mario World into a completely different game.
Sethbling elaborates in the video, which you can watch below, that it should take an hour if he doesn’t make any mistakes. If he makes even a single mistake, two things can happen. The game will crash, or he will have to start the section over again. MrCheese is also thanked in the video for the route Sethbling is taking.