A very good ROM hack with interesting mechanics added, like interaction with the environment (using your Pokémon to turn on some lights or lit something on fire to progress), new types, a huge cast of Pokémon, with a lot of Pokémon from the 3D games included with amazing 2D sprites, good (at times) custom music, and a focus on making the game more nuanced than your regular Pokémon experience, sometimes to its detriment, as some dungeons can feel long-winded.
There are some bugs that could halt your progress, but I found playing with a guide at hand to make that issue disappear.
This game is a recommended one for anyone who likes Pokémon and wants a longer, more involved experience.