Warren Spector and Harvey Smith, the creative directors behind the first two games, were not attached to the project.
In the Deus Ex games, augmentations are body modifications that allow the user superhuman abilities. While augmentations in the first two games were nanotech, Human Revolution is set prior to both and instead features mechanical augmentations. These will be divided into four types: Combat, Stealth, Technology and Social. Using social skills, social augmentations, and stealth a player is able to play through the whole game killing only the bosses.
Every enemy squad will have an identifiable squad leader who will direct the team's actions. If the leader is killed, the squad falls into disarray. Enemies will also react to subtle player decisions, such as a change in behaviour or weapons, etc.
Unlike in Deus Ex: Invisible War, weapons will fire distinct ammunition types instead of depleting a unified pool. They can also be upgraded to better suit the player.
In a controversial departure from previous titles in the series, Human Revolution will use a regenerating health model. This change was made because the developers didn't want players to get into a situation where they were unable to progress due to low health, and would be forced to "scrounge for med packs."They see this scrounging behaviour as breaking the flow of the game when one retreats to search the entire level for medical supplies. They believe their regenerating health model will still encourage tactical and strategy forming retreats, but not to the extent where the tension and flow of the game is disrupted.
Human Revolution is primarily a first person game, but will feature a contextual third person viewpoint when using the cover system, certain augmentations, or closeup instant-kill moves.
The game takes place during the year 2027, 25 years before Deus Ex. Nanotechnological augmentations have yet to be developed and bio-mechanical augmentations are the current state of the art. The main character, Adam Jensen, is a private security officer with Sarif Industries a leading company that specializes in these augmentations. After he witnesses a chilling attack on his company which leaves him horribly injured and forced to undergo augmentation to survive, "the conspiracy begins."The visuals are a combination of cyberpunk and Renaissance aesthetics, resulting in a futuristic-looking Baroque world. Adam Jensen will be voiced by Elias Toufexis.
The player will visit five metropolis' during the course of the game, including Detroit, Shanghai and Montreal. In addition, the protagonist will have his own apartment where he may store his secrets and collected information. The events in the game will lead to the formation of UNATCO from the original game.
Human Revolution deals with the ethics of transhumanism, and carries an overarching message of humanity's reach exceeding its grasp. "Mankind is using mechanical augmentations," director Jean-Francois Dugas said before the game's release, "but there is still much to be determined in terms of their effect on society and the ultimate direction it will lead us in." The Greek myth of Daedalus and Icarus appears in Adam Jensen's dreams as an allegory to this thought, and also—given that both Daedalus and Icarus were the names of artificial intelligences in Deus Ex—an intellectual bridge to the original game.
The pace of technological development is reflected visually by a Renaissance theme. Characters who support the advances of human augmentation dress themselves and decorate their homes in reinterpreted late-medieval Italian style, and the game as a whole has a sepia-tinted colour palette reminiscent of historic manuscripts. In contrast, characters who oppose augmentation wear clothing that is more or less current-day.
As was the case in Deus Ex conspiracy theories and immensely powerful corporations feature strongly, but nothing is currently known about them.
An initial teaser trailer was released on November 26, 2007, and around one year later PC Zone Magazine ran a first preview which detailed some of the game's mechanics and setting and provided the first true artwork and screenshots. Several of the design decisions mentioned, most notably the switch from health packs to regenerating health, precipitated an initial backlash amongst many fans of the original Deus Ex.
In November 2009 it was announced that Square Enix was to publish the game, and that the CGI sequences were to be created at its Japanese Visual Works studio with direction from Goldtooth Creative in Canada. The results of this international partnership were first seen in the teaser trailer shown at the 2010 Game Developers Conference (by which point the game's subtitle had changed to Human Revolution and its release pushed back to "early 2011"), which was expanded to a three minute trailer at E3 2010. E3 2010 also saw a second major preview of the game, this time in PC Gamer UK, which provided engine-rendered screenshots and gameplay details.