Official story and features:
"Attention all Hunters - a new mission awaits you. To begin your assignment, you must land on Planet Ragol via an alternate spaceship known as...the Nintendo GameCube! In this latest version of Sonic Team's award-winning RPG series, you get two games in one. Episode I gives you all the hit content and gameplay from the original PSO and PSO ver.2. Episode II brings a new full-length adventure that's exclusive to the Nintendo GameCube. You'll face real-time combat with enemies that are more powerful than ever before. New levels, like the breath-taking mountain and beach stages, give you expanded areas of gameplay and deep, lush worlds to explore. You'll also be given all-new quests to complete, additional weapons to master, and lots more rare items to find. Choose your character from the original 3 classes, each with a fourth new being. For intense offline gameplay, team up or compete with up to three of your fellow Hunters on the same console for a split-screen battle. Go forth Hunter, and bring glory to the Guild..."
Story from Sega site
"- New split-screen action lets up to four heroes team up or compete on the same Nintendo GameCube.
- All of the content from PSO and PSO ver.2, plus a new full-length adventure.
- Test your endurance with Challenge Mode, or reign as the supreme champion of player vs. player combat in Battle Mode. - Real-time combat against new, more powerful monsters.
- New dungeons and areas to explore, new rare items to find, and new quests to download!"
Features from Sega site