It's Pokémon Uranium, which is undoubtedly bold - it has its own area and all-new characters and Pokémon, along with online trading and battling. Check it out below.
Pokemon Uranium is a fan-made Pokemon RPG that has been in development for over 9 years. Set in the tropical Tandor region, the player will encounter more than 150 all-new species of Pokemon in their quest to collect all 8 Gym Badges and triumph over the Tandor League. Along the way, the player must battle against a sinister threat that's causing Nuclear Meltdowns, and will encounter an all-new type of Pokemon: the Nuclear type.
Unsurprisingly the official website and download links for this are currently the victims of melting servers, to the point that an alternative has been setup (which is live at the time of writing); players are evidently in a hurry to catch it while they can.
Once again it's a not-for-profit fan-made effort with plenty of blood, sweat and tears behind it, yet is likely to be on dodgy legal ground. Even with a trailer that says "please support the official games", it'll be interesting to see whether this gets targeted for a shutdown by Nintendo.
There's huge interest in it right now, and it'll be intriguing to see how long it stays available.
With thanks to Benson for the heads up.