Deus Ex was a brilliant, intelligent game, full of depth and interest... it's graphics were only just good even at the time, but it was so well written that your imagination literally filled in the gaps.
All the basic troops used exactly the same model, and there were only a few doctors/scientists that filled all those roles, but somehow they were interesting characters, with brilliant back stories scattered around in emails and notes to one another, and conversations that were scripted in to start if you got near, many of them only if you weren't seen.
I wish they'd remake it Metal Gear Solid Twin Snakes style; same story, same basic rules and gameplay, but with greatly improved AI and of course updated graphics.
Or better yet make another immersive tech-conspiracy fueled linear roleplaying stealth exploration shooter with a steep difficulty curve and some otherwise near impossible objectives being the main things to make you try stealth, and serious upgrade benefits making you take lots of time and risk exploring. No need to call it deus ex, we'll get the picture.
The key to this game's immersive power is not the multi-linear aspect, as this was strictly limited. It's in the conversations and actions available to you. I have gone out to read books briefly refered to in Deus Ex. I felt after playing that I know more about international security, about the nature of humanity and about the world that we live in than I did before.
"Deus Ex 2 Invisible War" was an okay game, with a pretty decent main story, very poorly executed because it was dumbed down for a console audience.
Weapons, equipment etc. no longer took up inventory space limiting you from carrying lots of big weapons. In the original this forced you to make choices.
In the sequel, the previously game winning augmentations were so freely available that there was no challenge to obtaining them, and so less incentive to follow the few side explorations that they bothered to add. These that you received were improvements, but largely unnecessary ones, as the game was so much easier it was at many points ridiculous.
The maps felt tiny and boring, and attempting to explore them Deus Ex style just led you to areas they never finished making. I fell off the map a dozen times or more.
The side missions were clearly designed to explain corporate conspiracies to a six year old, with revelations of the way the world works that the writers apparently thought would shock the character into action, but instead just made the game seem idiotic.