Pokémon has been recreated using Garry's Mod with some very wacky results.
The first episode of Garrymon answers the question: what would the Pokémon television show be like if it were created by Valve? The answer, is something completely absurd. Two YouTube members are responsible for the development of this 11 minute long episode, which faithfully recreates specific segments from Pokémon, but also throws in lots of weird faces courtesy of Half-Life 2's Garry's Mod.
Garrymon is surprisingly creative, but also incredibly (and intentionally) dumb at the same time. Pikachu is a headcrab, the Pokédex is now the Gabedex (complete with Gabe Newell's face), and the main character is just a whiny as Ash from the original Pokémon show. It follows the format of a typical Pokémon episode, beginning with Ash yelling about how he's going to become the best and such, attempting to do so and getting harmed in various ways, and ending with Ash somehow winding up victorious against all odds.
The Garrymon creators don't plan to stop here, with episode 2 currently in production. They've already demonstrated the ability to make lots of silly Garrymon using all of the tools available in Garry's Mod. It's one of those odd combinations that somehow makes perfect sense at the same time. My attention is usually diverted after 30 seconds of any video by the massiveness of the internet, but Garrymon managed to keep it for the full 11 minutes. I'm waiting for the introduction of the show's Team Rocket, which should probably become "Team PS3" due to Sony's inability to get Valve to develop for the console. Well, it's an idea anyway.