Gamasutra has a fairly detailed summary of a talk given by David Anfossi, producer at Eidos Montreal on Deus Ex: Human Revolution's development at this year's Montreal International Games Summit. Here's a generous snip from this interesting read:
"Respecting" Dues Ex meant replaying the games, documenting their experiences, and making sure that the studio as a whole understood the essence of the series. "It's very important. Respect the initial invention," he said.
Aside from playing the original Deus Ex and its sequel, Deus Ex: Invisible War, the team also delved deep into cyberpunk research. The studio read Neuromancer, Count Zero, Singularity and Humanity+ magazine, among literature. They also watched the Ghost in the Shell Series, Bladerunner, and other Cyberpunk-styled media.
And despite the name of the game, part of the mandate for Deus Ex: Human Revolution was not to make it a revolutionary game, said Anfossi. "Our challenge now is to turn it into a gamers' franchise," he said, and fix the perceived flaws that kept the series from gaining a wider audience.
It was time to go into pre-production. During this phase, the studio opened up a line of communication with gamers. Even before the release of a trailer, the studio opened up an online forum. "We received very strong feedback," laughed Anfossi. He flashed examples of "feedback" on a slide. "Don't fuck it up"; "Don't touch this franchise"; "Don't do another Invisible War"; and in a reference to the designer behind the original Deus Ex, "Forget it, Warren Spector is not part of this team."
"It was very hard to receive constructive feedback," Anfossi said. "It's good to listen to gamers, but there is a time to do that correctly."