Super Pokemon Eevee Edition is a remake of classic Pokemon games with other elements like battle systems and role-playing.
It's designed to combine a few different elements including retro graphics, a battle system from Final Fantasy and a story involving godlike entities, called hypervisors. It mainly takes the Pokemon formula and mixes it with elements of an RPG, primarily similar to the old Final Fantasy style of gameplay. There are numerous side quests and achievements as well.
The result is pretty impressive.
The storyline features the main character, Gold, who is a rookie Pokemon trainer. He is tasked to kill the hypervisors and stop the apocalypse.
Luckily, you're not alone. Helping you is your starter Pokemon, a special Eevee which can switch between evolutions at will.