Super Mario World is one of the most beloved games ever made, and that has led to fans breaking the game open in order to figure out how they can change it and manipulate it. And now someone has taken this to an extreme new high.

YouTube personality SethBling has uploaded a new video where he goes through a process to inject 2014 sensation Flappy Bird into Super Mario World by hand. Using a number of well-known glitches and by positioning Mario at certain coordinates in one Super Mario World’s levels, SethBling was able to write several lines of code into the game’s memory. This is something we’ve seen other people do before using the tool-assisted robot (TASbot), but that enables players to predetermine a number of controller inputs that the TASbot will then feed to the Super Nintendo. In this case, SethBling actually hand-controlled every piece of this process — he pointed out that this is likely the first time anyone has ever coded another game inside of Super Mario World without computer-controlled assistance.

In the video, SethBling explains the process, and you should watch that to really understand how he did this. Put simply, he used the “powerup” glitch to make it seem like Mario had reached the 21st level of his powerups, which doesn’t exist in Super Mario World (he only goes from small at 0 to cape at 4). This tricks the game into running code anytime Seth ran into a mushroom. He then added code to the game that enabled him to display Mario’s X position where you would normally see how many coins he has. Those X positions — or where Mario is standing in a horizontal relationship to the level — act as the values in the code Seth wrote. He could write them into memory by doing a spin jump with Mario.

With all of those basics in place, SethBling then wrote 331 instructions into memory using the process of moving Mario around and spin jumping. The result was an executable version of Flappy Bird, which you can check out in the video at the top.