The more interesting Deus Ex-related Extra Punctuation would probably be the one that follows my Human Revolution video, but for right here and right now there're a couple of things to talk about exclusively relating to the first Deus Ex. Don't fasten your seatbelts too tightly, now.
I'd almost go as far to say that the first Deus Ex came out of a sort of golden age for first-person PC games circa the end of the last millennium. Half-Life and its wayward children Counter-Strike and Team Fortress Classic were the least of it; this was a time when the model of the shooter was being challenged on all sides by games like Deus Ex, Thief, System Shock 2 and Hitman (and arguably Morrowind). Each game to a man possessing considerably more depth than the mainstream games of today, and the main reason for my recurring claim that the unwieldiness of modern technology has led to creative devolution. Incidentally, Looking Glass Studios, which brought us Thief and System Shock, was one of the companies that went down in the sucking Eidos whirlpool caused by, amongst other things, the spectacular failure of John Romero's Daikatana. Then Thief 3 - or Deadly Shadows - had to be developed out of Ion Storm Austin, the Deus Ex people. Marvel at the interconnectedness of all things. The games industry is basically as incestuous as a Louisiana farming community.
This period was almost the equivalent of what the PS2 era was to console gaming: a sweet spot when technology was advanced, but not so advanced that developing for it was hugely shackling, and games had room on their disks to spread out and explore the depths of the medium. Thief: Deadly Shadows was almost a symbol of how it would all go wrong; the chubbier graphics and hardware meant the levels had to be split, smaller and less open-ended than the somewhat uglier Thief 2, and so the pressure to look good brought with it the age of gameplay compromise.
The thing about games from this period is that they were also somewhat loosely bound together. As what happens when you push an older engine until it's swollen and bloated, a few cracks start to appear that some smart bugger somewhere will learn to exploit. On the one hand this means that even today there are huge modding communities for these games adding whatever gameplay or graphical tweaks the fans think are necessary, but it also meant the games were rather easy to break. Sites like it-he.org exist solely to catalogue the many ways games like Deus Ex could be ruined without even needing to cheat, generally by stacking pseudo-physics objects to get to places you shouldn't, or (in one of the highlights on the linked site) getting the entire staff of UNATCO to attack the same invincible vacuum cleaner robot.
These flaws are part of the attraction. It gives the games a sense of loveable experimental fun that later, snobbier games lacked. It felt more like the developers and players working together to create the playing experience rather than developers looking down on players as troublesome elements in the game that have to be herded into line. I guess the point I'm getting to is that there was no better time in the history of gaming for acting like a complete jerk.