Pokémon Gold, and its sister, Pokémon Silver, are of the next generation of Pokémon, after Pokémon Red and Blue.
Among noticeable differences is that the game is now colourful, and that there are over 250 Pokémon instead of around 150.
This movie plays through Pokémon Gold in a fairly fast manner, catching only a half dozen Pokémon in the process, but acquiring all the gym badges, and ultimately beating the protagonist of the earlier generation Pokémon games.
The author of this movie, FractalFusion, has written very extensive details of anything regarding this movie, including even some of the mathematical formulas used by the game. As usual, we recommend reading it.
This is a tool-assisted speedrun, made on an emulator, using frame-by-frame shooting, savestates, and rerecords to overcome reaction time and human error. As such, it is purely a form of entertainment, and is not designed to show skill.