Pokemon Elysium (ROM hack)

Pokémon Elysium is a highly-rated, story-rich fan-made Pokémon ROM hack known for its extensive lore, multiple regions, and unique gameplay features. It is widely considered one of the best story-based ROM hacks available.
Key Features
Story & Lore: The game is centered around a deep and engaging original story, often compared to an epic saga like Lord of the Rings, which takes the player on a journey across multiple regions, culminating in a grand championship on the mysterious Elysium island. The story involves an ancient dark presence threatening the world.
Gameplay:
Length: It is significantly longer than typical Pokémon games, split into two main parts (Part A and Part B), with a prologue, four chapters, and an epilogue.
Regions: Players can explore several brand-new regions and towns.
Pokémon: Features a mix of Pokémon from Generations I through VI (up to X and Y), incorporating the Physical-Special split and the Fairy type. It includes some story-only related "fakemon" (fan-made Pokémon) but has very limited use of them overall.
Difficulty: The game offers a challenging experience, harder than official Pokémon games, with an organic level curve that can take Pokémon all the way to level 100.
Side Quests: The game is praised for its detailed and rewarding optional side quests.
Trade Evolutions: It is a ROM hack, so "trade" evolutions like Haunter into Gengar or Seadra into Kingdra typically involve alternative methods within the game, often using a specific item or an in-game NPC, without requiring an actual trade with another player.
Availability: As a ROM hack, it requires an emulator to play. It is a free, fan-made creation and can often be found on community forums like r/PokemonROMhacks on Reddit or the PokeCommunity website.