Players control the special agent Leon S. Kennedy on a mission to rescue the US president's daughter, Ashley Graham, who has been kidnapped by a religious cult in rural Spain.

Four proposed versions were discarded; the first was directed by Hideki Kamiya, but series creator Shinji Mikami felt it was too great a departure from the previous games, so it was spun off as Devil May Cry (2001).

Based on the situation, players can interact with the environment: kicking down a ladder, jumping out of a window, dodging an attack or executing a "finishing move" on weakened enemies.

There are also quick time events, in which the player must press buttons indicated on-screen to execute actions such as dodging a falling boulder or wrestling an enemy to stay alive.

Unlike the franchise's traditional zombies, they can dodge, wield weaponry like chainsaws and projectile weapons, and are capable of working collectively and communicating with each other.

The largest addition is "Separate Ways", a side story which focuses on Ada Wong's involvement in Resident Evil 4 and her connection to the series' villain Albert Wesker.

[10] In 2004, U.S. government agent Leon S. Kennedy (Paul Mercier) is on a mission to rescue Ashley Graham (Carolyn Lawrence), the U.S. President's daughter, who has been abducted by a mysterious cult.

He discovers that one of his former training comrades, Jack Krauser (Jim Ward), who was believed to have been killed in a helicopter crash two years prior, is responsible for her kidnapping in an attempt to get close enough to Saddler to steal his new Plagas sample.

[30] The story was based on unraveling the mystery surrounding the body of the protagonist, Tony,[31] an invincible man with skills and an intellect exceeding that of normal people, with his superhuman abilities explained with biotechnology.

[28] As Kamiya felt the playable character did not look brave and heroic enough in battles from a fixed angle, he decided to drop the prerendered backgrounds from previous installments and use a dynamic camera system.

[27] The team spent 11 days in the United Kingdom and Spain, photographing objects such as Gothic statues, bricks, and stone pavements for use in textures.

[40] The game saw Leon S. Kennedy struggling to survive[39] after having infiltrated Umbrella's castle-like main headquarters located in Europe and featured traditional Resident Evil monsters such as zombies.

[26][41][42] During the course of the new story which was again written by Sugimura's scenario creation company Flagship,[43] Leon became infected with the Progenitor Virus and possessed a hidden power in his left hand.

[47] The story was set in a haunted building where Leon contracted a bizarre disease and fought paranormal enemies, such as animated suits of armor, living dolls, and a ghostlike man armed with a large hook.

[26] It also displayed various gameplay mechanics that carried over to the final release, like the over-the-shoulder camera, a laser sight for aiming in battles and quick time events.

In 2012, Resident Evil 3: Nemesis scenario writer Yasuhisa Kawamura said he was responsible for this version, as he wanted to make Biohazard 4 scarier "and suggested using a particular scene from the film Lost Souls, where the main character [...] suddenly finds herself in a derelict building with a killer on the loose.

[59] Inspired by Onimusha 3: Demon Siege, a game Mikami had enjoyed playing but felt could have been better with a different view, he decided to place the camera behind the playable character.

[60] To go along with the new gameplay and story, a new type of enemy called "Ganado" was created, as opposed to using the undead creatures from previous Resident Evil games.

[62] Kobayashi described the creatures' origins within universe lore as byproducts of Los Iluminados' research into bio organic weapons, malformed creations implanted with multiple Plaga parasites during the experimentation process.

[73] The Wii Remote is able to aim and shoot anywhere on the screen with a reticle that replaces the laser sight found in the other versions, and motion-based gestures are used to perform some context-sensitive actions, such as dodging or slashing.

[87][88] On July 13, 2009, without any formal announcement, Resident Evil 4: Mobile Edition was released by Capcom for the iOS platform via the App Store in Japan, but was quickly removed,[89][90] though some players were able to purchase and download it.

On July 23, 2011, Capcom announced at Comic-Con 2011 that Resident Evil 4 would be released on September 20, 2011[93] for the PlayStation Network and Xbox Live Games on Demand.

The original PC port was criticized for no mouse support and frustrating keyboard controls, low-quality FMV cut scenes, and choppy lightning graphics rendering.

Despite these problems, it received generally positive reviews from critics,[112] including IGN and GameSpot, which praised the gameplay, character models and environments, and sound design.

[222] Resident Evil 4 is regarded as one of the most influential games of the 2000s, particularly due to its influence in redefining the third-person shooter genre[223] by introducing offset camera angles that do not obscure action.

[225] The over-the-shoulder viewpoint introduced in Resident Evil 4 has later become standard in third-person shooters and action games, including titles ranging from Gears of War to Batman: Arkham Asylum.

[223] It has also become a standard "precision aim" feature for third-person action games in general, with examples including Dead Space, Grand Theft Auto, Ratchet & Clank Future, Fallout,[226] Uncharted, Mass Effect and The Last of Us.

[233] Other major survival horror series followed suit, by developing their combat systems to feature more action, such as Silent Hill: Homecoming[231] and the 2008 version of Alone in the Dark.

[236] Dead Space designers Ben Wanat and Wright Bagwell stated that their game was originally intended to be System Shock 3 before the release of Resident Evil 4 inspired them to go back to the drawing board.

[243] In June 2021, the photographer and author Judy Juracek launched legal proceedings against Capcom for using images from her book Surfaces: Visual Research for Artists, Architects, and Designers without her permission to create textures for multiple games, including Resident Evil 4 and Devil May Cry.