Odds are you're already familiar with Counter-Strike, but in case you're not, the game pits a team of terrorists versus a team of counterterrorists, and the gameplay falls somewhere between frantic team deathmatch and realistic tactical-shooter action. Combat is usually very fast paced, with weapons inspired by real-world counterparts; teamwork is a must if you want to win. Gameplay is divided into short rounds that typically last just a few minutes. Each team has specific goals, depending on the map; almost always these revolve around planting/defusing a bomb or holding/rescuing hostages. As you complete goals and kill enemies, you earn cash, which you spend on weapons and gear when a new round begins. If you're killed during a round, you have to sit out the remainder of it, watching the action in a spectator mode.

Condition Zero dishes up more of this tried-and-true Counter-Strike gameplay, but what sets it apart is its new offline modes. One mode is a ladder-based tournament, playable only as the counterterrorists. After selecting a difficulty level, you progress through six "tours" of three maps each. Within the current tour, you can tackle the maps in any order, but other tours and their maps have to be unlocked sequentially.

For each map, you work through a series of rounds where your team has to stay in the overall won-loss lead while you also try to complete personal challenges (like killing three terrorists with a particular sniper rifle). You keep playing on the same map until your team has won a certain number of rounds and you've completed your personal goals. By winning, you gain more reputation points, which you use to select increasingly skilled bot teammates before beginning the next map. However, if the terrorist team gets too far ahead in the won-loss column, you lose on that map and have to retry it from scratch.

While there's nothing innovative about all this, it does provide a little extra structure and added goals to what's otherwise the standard Counter-Strike gameplay. Some real innovation would have been great, but at least the regular Counter-Strike gameplay is as solid as ever: straightforward, elegant, easy to learn, and hard to master. Matches boast an addictive blend of brutal, lightning-fast firefights and some careful, silent stalking. They're filled with sudden shifts in momentum and miraculous last-second victories or humiliating defeats.

To play online, you'll need to use Valve's Steam service, which offers content delivery, automatic patching, and server browsing. Actually getting Steam properly installed and configured was a lengthy and tedious chore, but after that it worked smoothly.

If you want to enjoy this classic gameplay offline without working through the ladder, you can simply start up a standard match with bots. It would have been nice to have deeper configuration options for the bots, but at least these matches let you play as the terrorists, unlike the tournament. In addition to playing offline, you can use Condition Zero to play online Counter-Strike or Condition Zero matches with other humans. The only major difference between these is that Condition Zero lets you fill out a server with bots, and some maps have been slightly tweaked.