Witcher-style gameplay. All Pokemon have mysteriously turned rogue and completely savage, and destroyed the world. It's like a zombie apocalypse but with Pokemon instead of the zombies. You play a young man/woman who owns one of the last non-feral Pokemon in the world (you get to choose it out of a few options in the beginning of the game, which will determine your playstyle. Like choosing a class in most other RPG's).
And it has blood and gore and all that, Pokemon battles to the death. And you can loot dead Pokemon for food and supplies and stuff.