Veteran designer Warren Spector has always been known for making games that combine action and role-playing elements within seamless 3D environments in order to create the most plausible interactive worlds possible. He's worked on such critically acclaimed game series as Ultima Underworld, System Shock, and Thief, and his latest game, Deus Ex, is similar. It's an ambitious 3D game that defies simple classification, and though some of its individual elements are either overused or underdeveloped, the aggregate experience of playing Deus Ex proves to be both unique and worthwhile.

Deus Ex looks like a first-person shooter and frequently plays like one. As bionic government agent J.C. Denton, you're issued a series of risky covert assignments by your employer, the United Nations Anti-Terrorist Coalition (UNATCO). You'll find a wide variety of melee weapons, pistols, rifles, experimental guns, and explosives over the course of your missions, and you'll also get to use an assortment of miscellaneous high-tech equipment for infiltration and espionage. While J.C. can immediately use any item or weapon he finds, he's initially inexperienced with most of them. Fortunately, J.C. earns skill points for completing his various objectives, and these can be applied at any time to augment J.C.'s various special abilities and combat skills up through four levels of proficiency. Denton might also encounter various weapon modifications during his missions, which can slightly improve his weapons' kick, reload rate, and range, as well as add features like a silencer and a laser sight. You can apply additional modifications to the same weapon, and together with the ability to improve your skill with that particular weapon type, eventually you can go from being a lousy shot to a deadly sniper. But in choosing that route, you will forgo specializing in such skills as computer hacking, lockpicking, and swimming, which are some of the skills that you can apply in order to completely circumvent a lot of potentially violent situations in the game.

Deus Ex is quite long for an action-packed first-person game, but even so, most of its situations present you with two or three possible solutions. There's usually a direct approach, in which you must kill or incapacitate a great number of enemy gunmen along the way. But most every entrance in Deus Ex also has a back door, and you'll avoid having to use up your ammunition if you find it. The game also gives you several overlapping options to facilitate problem solving and to help keep you from getting stuck or frustrated. For instance, at several points in Deus Ex, you'll have to jump underwater and swim to reach a particular destination. Your average swimmer couldn't do it, but J.C. Denton isn't your average swimmer: You can increase J.C.'s swimming skill, thus letting him swim faster; you can acquire a bionic augmentation that improves J.C.'s lung capacity, which lets him stay underwater longer; or you can improve his environment training skill, which lets him get more use out of underwater rebreathers, hazard suits, and other special gear. Any of these options are viable in any combination.

Each mission in Deus Ex inevitably involves getting past many enemies, security systems, and locked doors. Just as you could engage these foes and find the appropriate keys in all instances, so can you sneak past your foes and their security measures by staying out of their line of sight or, later in the game, using high-tech stealth camouflage to slip right past them. As for the doors, you can either pick their locks or just blow them off their hinges if you can't find the key. Most importantly, as you play Deus Ex, you never need to pigeonhole yourself as a gunslinger, a saboteur, or a thief - your proficiencies grant you only moderate benefits until much later in the game when you can really emphasize your favorite abilities. But until then, you'll be able to improvise in most every situation. You might typically prefer to take the first shot, but if you're low on ammo, it's good to know that you could always just sneak through a particular sequence until you find more.

Deus Ex's open-ended design is certainly ambitious, and for the most part, it's successful. There's a lot of background information in the game that's purely optional; you'll come across books, newspapers, and e-mail messages that are interesting and contextually pertinent, but you needn't dwell on them for long. You can continue to hound many of the characters you encounter long after the main thread of the conversation is over, which often yields valuable but nonessential clues. These characters might refer to how you've approached situations in the past, and it's startling and remarkable when they do. If you tend not to take prisoners, one UNATCO coworker might laud you for making short work of the coalition's terrorist foes, but another more even-tempered peer might give you the cold shoulder for cruelly killing UNATCO's opponents instead of finding a more humane solution. Most of the characters you meet in Deus Ex will behave differently toward you in later sequences depending on their first impressions. You don't often get to choose your responses during dialogue, but J.C. generally does a good job responding to others based on how you've been playing the game. Unfortunately, character interaction tapers off in the game's middle third, in which you'll find yourself constantly undergoing fairly repetitive infiltration missions. It's at these times, when you're closely attending to the means of accomplishing your goals, that you'll best be able to identify the game's weaknesses.