The game takes place during the same time frame as the films. With the characters usually right behind the Fellowship. Although eventually the main party catches up to the fellowship at Helm's Deep.
The game features turn-based rpg combat that was made famous in the Final Fantasy series of games.
The game only had the rights to the material from Peter Jackson's films. And so contains no content from J.R.R. Tolkein's novels that wasn't featured in the movies.
The game contains a complete digital replica model of Helm's Deep as seen in the films.