According to the game’s website, the game itself has over 150 original Pokemon and “aims to recapture the classic Pokémon experience along with some added twists.” From the gameplay shown in the launch trailer, it gives the impression that it lives up to its goals.
If this is something you’re interested in, you should hurry to download it here, or check out the game’s Twitter page for more information. Nintendo is strict about protecting their IPs, Pokémon being no exception.
Apart from this fan release, Nintendo does have an official duo of titles, Pokémon Sun and Moon, taking players to the new lands of Alola, arriving on November 18.