Official story and features:
"Phantasy Star Online Episode III: C.A.R.D. Revolution expands the Phantasy Star Online (PSO) universe, offering a new style of strategic combat. Combining the excitement of card collection and deck settings with team-based battle tactics, PSO Episode III allows users to chat in the lobby about status upgrades and tactics, and then journey to the planet surface to engage in strategic combat using a turn-based Card system. The game continues the story arc of the previous PSO games, as players once again become Hunters and explore the mysteries of the planet Ragol. Featuring both online and offline play, as well as multiplayer modes, PSO Episode III adds new content and players to the ever-growing PSO community."
Story from Sega press release
"- Play online and interact with Hunters from PSO Episode I & II in the lobby
- Engage in offline team battles for up to four people, where players are divided into friends and enemies
- Choose from either the Item Deck or the Enemy Deck, depending upon whether you will fight as a member of the Hunters or the Arks (enemies)
- Collect an enormous number of weapons, gear, and items to create an original deck with your character
- Use Action and Assist cards to compose a powerful deck, supported by Hunters and Items or Bosses and Enemies
- Position your characters on the battle field and move them as the battle unfolds to take advantage of your opponent's weaknesses
- The next chapter in the PSO universe continues the story of PSO Episodes I & II"
Features from Sega site