The Ghosts are back. After first appearing in last year's tactical shooter Ghost Recon, this fictional team of elite US soldiers returns in Desert Siege. This expansion pack takes you through eight single-player missions in the sands of Africa and adds welcome new multiplayer options to the original game. It also features some subtle but important improvements to the original gameplay that make Ghost Recon a more polished and enjoyable game as a whole.

The Desert Siege levels look much better than those of the original.

The setting of Ghost Recon was pretty typical: You battled your way through former Soviet states threatened by Russian ultranationalists. Desert Siege offers up a more unusual setting. This time, you'll help Eritrea stave off an invasion led by an Ethiopian dictator. At first, this may sound pretty obscure, but it's actually quite topical. In real life, Eritrea won its independence from Ethiopia only about 10 years ago after decades of war. Fighting flared up again between the two nations just a few years ago. Plus, images of US troops fighting in sandy wastes or in Africa itself have become familiar through US operations in the Persian Gulf, Somalia (Ethiopia's neighbor), and Afghanistan.

In the single-player missions, you'll get theoretically varied mission objectives, though they almost all boil down to one thing: Very gingerly wend your way through the maps, picking off enemies from afar. Expect relatively little in the way of extended firefights or close-quarters battles, but expect loads of sneaking and sniping. The missions aren't especially original, though they vary enough to be entertaining overall.

More than any particular combat encounters, what stands out about the missions are the environments themselves. The towering refinery of the second mission is particularly impressive, and a railroad yard provides the opportunity for some intense sneaking in a later mission. Some of the missions take place at night, but the daylight ones have the added benefit of showcasing Ghost Recon's graphics engine. The blazing sun lets you appreciate the visual details far more readily than the shady areas found in many of the original Ghost Recon missions did. The textures and animations (other than the slow-motion enemy deaths and dated-looking explosions) generally look really impressive.

The core single-player gameplay of Ghost Recon remains essentially unchanged in Desert Siege. Before each mission, you get a briefing describing core and bonus mission goals. You also get a rudimentary map of the mission area. After studying the situation, you fill up to three fireteams with soldiers of your choice. Each team can include up to three men, though you can enter a mission with only six men total. You can assume the role of any of these soldiers at any time during a mission.

Your squad members will do a noticeably better job in combat.

Each soldier has a specialty, like rifleman or sniper, that determines what weapon kits you can select for him or her before each mission. Since each kit contains only two items (like a machine gun and extra ammo or an assault rifle and binoculars), you need to choose carefully based on the mission requirements and terrain. It does seem odd, though, that a soldier can't carry grenades, binoculars, and a rifle all at once. Also, you can't pick up dropped weapons or gear, so you'll need to restart the mission if you lose a soldier carrying a rocket launcher needed to take out a SAM site, for example. A bug that sometimes prevents you from reloading or switching weapons can cause the same end result.

By completing bonus mission goals, you'll gain access to specialist characters with otherwise unavailable weapons. Desert Siege adds five specialists with new weapons like the Russian PKM machine gun. For multiplayer games, you'll find even more new weapons. You'll get the M60 machine gun, familiar to anyone who's seen a Vietnam War documentary, and the FN-FAL Para Variant assault rifle designed for airborne troops. Quite a few Russian weapons are added, like the Groza assault rifle/40mm grenade launcher combo and the AN-94, scheduled to replace the aging AK-74. You'll get two new sniper rifles: the 7.62mm H&K PSG-1 and the Barrett M98, which fires a .338 magnum round. While these weapons don't substantially change gameplay, it's always nice to have a wide selection of firearms. You still can't see your gun barrel or sights in the first-person view, only a targeting reticle. Also, environments remain essentially indestructible.