Quoted By:
Pic related.
I thought the game had a better story than the Pokemon games. You entered a tournament that took place in an archipelago. The first round of the tournament, which was the bulk of the game, involved you searching for 10 pieces of "darkonium". However, there were 13 or so pieces of darkonium in the game placed in different locations around the archipelago. This gave the game a more open-world feel than Pokemon. Each island had a ranking based on difficulty. There was much more to the story, but I don't want to go into the rest.
Monsters also roamed around in the overworld, which made them feel like much more of a part of the world. Monsters would chase you. Flying ones would almost try to divebomb you. You'd see a bigass monster off in the distance and shit yourself. This isn't really something feasible for Pokemon to do in the main series, but it was a very nice touch.