History dictates that not much should be expected from mission packs for action games. Mercenary, the official expansion for Descent 3, barely exceeds such low expectations. While it offers more of what made Descent 3 great, its few good points are overshadowed by its generally bland level design and a lack of new features.

Both Mercenary's box and the official Interplay Mercenary site state that the game contains seven new single-player levels, four new "B-side" multiplayer levels, and a "variety of the best single and multiplayer fan-made levels." It's a rather unpromising start to the proceedings that the game's producer hasn't actually figured out exactly what's packaged with the game. As a service to the busy people at Interplay and anyone interested in purchasing Mercenary, it should be pointed out that there are no single-player fan-made levels on the disc, at least none that are actually installed or listed on the new game menu.

Which leaves, at least as far as single-player action is concerned, the seven Outrage-designed levels. Only two of the levels, the third and fourth, manage to match the quality of the best Descent 3 levels. The designers seem to have abandoned the outdoor rendering capabilities of the Fusion engine. A few missions have brief forays onto the surface, but for the most part you are once again trapped in the endless tunnels of the first two games. None of the levels even comes close to the visual impact of Descent 3's cityscapes.

The third mission is by far the best and almost makes up for the rest of Mercenary's relatively mediocre levels. Its lengthy task-list includes several exciting boss monster battles, some tricky shooting puzzles, and a timed, frenzied, and tense escape from the exploding complex. The fourth level is almost as good as the third and will have you forgetting about the blandness of the first two.

However, that memory will come rushing back during missions five through seven. They're long but completely and noticeably forgettable. The final boss is also a letdown. Its lair is a simplistic boxlike structure, and fighting it offers no unexpected events, nor does it require any ingenuity on your part.

Around ten new enemy robots have been added to the game. While the box states that they exhibit a new level of artificial intelligence, it's not readily apparent through simply playing Mercenary. Since the box is wrong about the single-player fan-made levels, it's hard to tell whether the artificial intelligence is actually improved or not. Also not included: any new weapons or multiplayer game modes. A new flyable ship is actually included, the Black Pyro, and while it handles a little differently from the other ships, it's not enough to get excited about. The one eye-catching graphical embellishment to the Descent 3 engine is the addition of a motion-blur effect on some of the enemies.

Politely discounting the fan-made multiplayer levels, only four professionally made multiplayer levels are provided. Though that's not very many, each is unique and actually fun. One is a castle reminiscent of Unreal's level design, another is a series of connected volcanic islands, the third is a pinball machine, and the last is a detailed re-creation of Outrage's offices. The levels are all gorgeous and clever, though not necessarily conducive to multiplayer action, especially the office. Had the developers displayed so much inventiveness in the single-player component of the mission pack, they might have made a mission pack whose quality approached the recent Half-Life: Opposing Force.

As it is, Mercenary is a somewhat threadbare mission pack that doesn't even live up to the expectations set by its own packaging. Hard-core Descent 3 fanatics might want to pick up Mercenary just to experience levels three and four and for the level-design inspiration provided by the "B-side" maps. Everyone else should just wait for Descent 4.