Deus Ex isn't famous for its modding scene the way that games like Skyrim and the Grand Theft Auto series are, but it's seen some ambitious projects since its release in 2000. One of these is community mod Revision, pitched as an overhaul to everything from the game's graphics and level design to its soundtrack. A few months before the mod was released, Revision's developers announced that they had gotten official approval from publisher Square Enix, which has another Deus Ex game coming next year. And as of today, it's officially available, with a launch trailer above.
Even more than usual for an old game, Deus Ex can feel dated or unapproachable, and while the new environments above don't change the fundamentally blocky nature of the world, everything is sharper and cleaner. There's a newly composed (and optional) score inspired by the original music. The mod is also supposed to include "new aesthetic and gameplay detail," which is a bit more nebulous. In older production notes, the team mentions adding additional paths or redesigned architecture in the game world, along with tweaks to the game's basic rendering capabilities. Meanwhile, some upgrades — like Revision's high-definition textures — were adopted from earlier mods.
Unfortunately, Revision is only officially supported on the Steam version of Deus Ex, although you can download the files independently on Mod DB. Fortunately, you can buy a copy of Deus Ex on Steam right now for slightly over $1.