Descent 3 is not your ordinary first-person shooter--and it never was. Instead of binding a player to the body of a military grunt or brawny mercenary, the Descent line puts the player in the cockpit of an agile and heavily equipped spaceship. Spiraling around the bowels of catacombs and pulling zero gs while decimating the enemy has long been the hallmark of this series. With version three, the game gets bigger. In addition, the expansion Descent 3: Mercenary builds upon the existing backdrop of the Descent 3 universe. Centered around the dark conspiracy revealed in Descent 3, Mercenary will have you flying as the leader of the Black Pyros, hired by Dravis to carry out his evil plans. The sky's the limit (almost, as there is a moratorium on altitude), and the players can now skim over enigmatic alien ruins and the bombed-out hulks of recent industry. Enemies are just as hard or harder to fight in open terrain, and some truly gifted behemoths will make players scurry for the familiar safety of the underground warren. But the most challenging aspect of this milieu is its vigorous use of all three dimensions. If players are too regimented in forward, back, and sideways moves, some nasty 3-D accelerated surprises await them. Of course, there's standard play for the lone wolf, but for those who like to fly in packs, there's the Internet module, which enables players to congregate and interact. Descent 3 is the ultraworthy heir to a gaming dynasty, so put your tray table in its upright position and adjust your attitude. --Tamara Hladik