The spinoff PlayStation Portable game "Crisis Core: Final Fantasy VII" delves into the past, specifically the history of Zack Fair, a member of the evil Shinra Electric Power Company's elite Soldier program.

Zack was a key player in the years before "Final Fantasy VII's" story line, we discover. Beginning the game as a midlevel member of Soldier, he carries out missions for Shinra while trying to figure out why his mentor betrayed him.

The game is divided into two big chunks and subdivided into lots of little slices. One chunk encompasses the missions that drive the game's story. These tend to be explicit assignments from Zack's superiors that send him out of Shinra's base city, Midgar, and they can get fairly complicated.

The second chunk consists of the dozens of minor missions that Zack can take on at any save point. They're bite-size bits of game play set in numerous locations.

The challenge is often high, and the rewards are often great. The fighting is a mixture of action and role-playing elements, with random factors thrown in.

"Crisis Core" has a unique element: the Digital Mind Wave (DMW) meter. This combat aspect appears as a slot machine that constantly cycles through character portraits. When it makes a match, Zack might, say, gain temporary immunity or be able to cast spells without using magic points. When the right conditions are met, the DMW meter activates a Limit Verge, generally a supercharged attack, or an improvement in Zack's level or one of his Materia spheres.

The DMW meter and Limit Verges make battles unpredictable. This randomness helps keep the combat interesting and fun.

The visuals are excellent in all respects. The music is a fantastic combination of remixed "Final Fantasy VII" pieces and pulsing rock, and the voice acting is superb.