Its unwavering commitment to letting players do things their way is what makes it great; its meticulous level design that really forces players to look at their surroundings as if they were really there is what makes it one of the most fulfilling RPGs ever. Deus Ex is a long string of kept promises, from the story premise of taking down the world government, bolstered by great writing, a dynamic soundtrack, and horrible but somehow tonally appropriate graphics and voice acting, to the genius use of permanency in the upgrade system that really puts the 'immersive' in 'immersive sim.' If there's a complaint to be made here besides some pretty sizeable balance issues, it's that it does get weaker the longer it goes on- the final few missions feel like they bleed together and certain third-act plot elements could've been handled much better- but it's worth it when you realize it's all been a wonderful set up for perhaps the only good end-game player decision ever. Grandiose, mature, and dare I say thought-provoking, long before the movie games of the modern age began to convince the world that these things couldn't be achieved without sacrificing player control.