Deus Ex: Human Revolution is a 2011 action role-playing game developed by Eidos-Montréal and published by Square Enix's European branch for Windows, Xbox 360 and PlayStation 3 in August 2011. A version for OS X was released in April 2012, and a "director's cut" version was released in October 2013 for the original platforms and Wii U. The third installment in the Deus Ex series, the gameplay combines first-person shooter, stealth, and role-playing elements. It features exploration and combat in environments connected to multiple city-based hubs, in addition to quests that grant experience and allow customization of the main character's abilities with items called Praxis Kits. Conversations between characters feature a variety of responses, with options in conversations and at crucial story points affecting how some events play out.

Set 25 years prior to the original Deus Ex (2000) in the year 2027, players control Adam Jensen, a security officer for Sarif Industries, a company which develops controversial artificial organs dubbed "augmentations". After an attack on Sarif, Jensen undergoes extensive augmentation and investigates the shadowy organization behind the attack. The story explores themes of transhumanism and the growing power of megacorporations and their impact on social class. It also uses the series' cyberpunk setting and conspiracy theory motif.

Development of Human Revolution began in 2007 with a small team within the fledgling Eidos-Montréal studio after failed attempts to create a sequel at original developer Ion Storm following Deus Ex: Invisible War (2003). The two key influences were the myth of Icarus, a thematic element carried over from Deus Ex, and the artwork and ideas of the Renaissance, which influenced the story, graphics, and music while combining with the series' typical cyberpunk elements. The open-ended gameplay was tricky for the team to achieve; the boss battles were outsourced to another developer due to time constraints. The music, composed by Michael McCann, focused on ambience and three-layered compositions over character themes and overt melodies. Human Revolution was announced in 2007, soon after its beginning development. Its title and release window were announced in 2010.

Human Revolution received critical acclaim for its player-driven plot, gameplay, and freedom of choice in the story and character customization. The major criticisms went to its boss fights and technical problems. The director's cut was praised for its revamped gameplay. After release, a downloadable episode titled The Missing Link was released, featuring gameplay and graphical updates, later being bundled with the director's cut. By November 2011, the original version had sold 2.18 million units. The game was followed up with a spin-off, The Fall (2013), and a direct sequel Mankind Divided (2016).

Deus Ex: Human Revolution is an action role-playing game incorporating first-person shooter and stealth mechanics. Players take the role of Adam Jensen, a man equipped with mechanical cybernetic implants called augmentations. The game's environments, ranging from open world hubs to more scripted environments, are explored in first-person, although actions such as hiding behind cover, conversing with non-playable characters (NPCs), and some attack animations switch to a third-person view. In these environments, players can find NPCs who will advance both the main story quest and optional side quests: completing quests, along with other actions such as combat with enemies, rewards Adam with experience points, which raise his experience level. Also accessible are black market vendors that supply equipment and weapons for Credits, the in-game currency. Interactive objects within environments can be highlighted, although these options are either turned off on the hardest difficulty or can be turned off in the options menu by the player.

There are various ways to approach the game's situations: players can use a violent approach and shoot their way through environments while using cover to hide from enemy fire. Alternatively, Adam can take a stealthy approach, avoiding/knocking out guards and security devices and using cover to avoid enemy sight lines. Adam can move between cover elements and around corners while staying hidden. The melee takedown system offers lethal and non-lethal options, in addition to an assortment of lethal and non-lethal weapons. Adam can also move the bodies of enemies into hiding places, preventing them from being seen and raising an alarm. A crucial part of Adam's abilities are augmentations, which can be acquired and upgraded using Praxis Kits either bought from particular vendors, found in the game environments, or are automatically unlocked by leveling up: higher-level augmentations require more Praxis Kits to unlock. Augmentation functions can range from passive enhancements to Adam's vision or damage resistance to active upgrades such as allowing Adam to fall from great heights without injury or increase his strength. Some augmentations depend on Adam's energy level, deactivating after an amount of energy has been drained.

At multiple points within the game, Adam partakes in conversations with NPCs related to main and side quests. When talking, Adam is presented with three different conversation options that affect the outcome of conversations: choosing the right option can help with completing objectives while choosing the wrong option closes off that route and forces the player to find an alternate solution. A "Social" augmentation enables better reading of an NPC's expression and judging their psychological profile, improving chances of selecting the correct dialogue option. While in the game's environments, Adam finds terminals and computers that can be accessed with a password or through hacking. When hacking, the hacking screen is summoned, which shows the pathway through a device's security system to access the information: the pathway is accessed by opening "directory" nodes to reach the registry. Different nodes have different ratings, affecting how easily they can be accessed. Various devices have different grades of difficulty, which dictate how often hacking may be attempted. Each hacking attempt activates a Diagnostic Sub-Routine that works to stop the hack, activating a time limit once it is alerted. Adam can use additional skills and items to lengthen the time, such as software to stop or instantly capture nodes or fortify captured nodes to increase the time limit. Successful hacks yield experience points, Credits, and sometimes additional items.

Human Revolution takes place in the year 2027, 25 years prior to the original Deus Ex. The Deus Ex series is set in a cyberpunk future rife with secret organizations and conspiracies: among these forces is the Illuminati. Leading up to Human Revolution, there have been marked improvements in human society, with people actively fighting global warming, finding cures for various diseases, and improving green energy. Alongside this, global megacorporations have come to eclipse government authority in power and influence, while private military forces dwarf the sanctioned armies of First World countries. Advances in biotechnology and cybernetics have led to the development of "augmentations", advanced artificial organs capable of significantly improving and enhancing the human body's performance. The development of augmentation technology has triggered a new social divide: those with augmentations become the world's new upper-class citizenry and are touted as the future of humanity, while normal humans form the majority of the lower-class population. Augmentations also require taking Neuropozyne, a limited and expensive immunosuppressive drug that stops the body from rejecting the technology. By the events of Human Revolution, society is being divided between "augs", humans who have accepted augmentation technology, and ordinary humans who are either morally opposed to it, too poor to afford it, or whose bodies actively reject it. The tensions between the two factions begin generating open conflict.