Deus Ex is a huge game (and one of my all-time favourites), with an involving and substantial storyline full of real-world conspiracy theories that takes the player all over the world–from New York to Hong Kong to Paris–playing through a considerable number of expansive and memorable environments such as the Statue of Liberty, a Templar cathedral, an underwater base and the streets of Hong Kong.
These environments are what set Deus Ex apart from most other first person shooters, because they're just that: environments, and not stringalong scriptfests where every door that doesn't take you from Point A to Point B is mysteriously locked. Instead, Deus Ex provides realistic settings and places you at the edge of the map, allowing you to choose how to proceed–through the front door with guns blazing or sneaking unobserved through a side entrance.
To this end the game provides a skill and ‘nano-augmentation’ upgrade tree that gives you the ability to play how you want: take melee weapon skills and the silent movement/cloaking augmentations to turn your agent into a close-striking assassin, pick up hacking skills to access security systems and turn turrets and robots against their owners, or just go for heavy weapon skills and blow everything up.
The Unreal Engine graphics may have aged somewhat since release, but anybody interested in absorbing, open-ended gameplay with a strong element of exploration, branching plotlines with interesting characters, dialogue trees and multiple endings needs to check this game out, especially at this price. Once you've played Deus Ex you might find it difficult to go back to the over-scripted, on-a-rail shooters that are typical of the genre.