According to Square Enix's official site, Radiata Stories will be showcased as a TGS2004 special version which includes exclusive quests to allow players into the world of Radiata Stories in the short time that they have playing.

There are two modes made available for playing. Selecting Event Mode, players can experience the opening of the game where you step into the role of Jack Russell to head for the Kingdom of Radiata to join the troops, and be assigned to Rose Cochon where you'll meet Ridley Timberlake. This mode has a lot of dialogue thrown between characters to get players into the story. Selecting Game Mode, players can group a party to go on quests with battles with enemies and bosses. This mode is more battle oriented, introducing its battle system to its players.

Each players will be provided with different party members, with different abilities and Link Battle settings. There are more than 150 playable characters... Also, depending on how you progress through the demo, the ending after defeating the boss will change aswell :D