Red Dead Redemption is a Western-themed action-adventure game played from a third-person perspective. The player controls John Marston and completes missions—linear scenarios with set objectives—to progress through the story; in the game's epilogue, the player controls John's son Jack. Outside of missions, players may freely roam the open world environment, consisting of the American states New Austin and West Elizabeth—fictionalized versions of the Western United States—and the fictional Mexican state of Nuevo Paraíso. Different breeds of horses are the main forms of transportation, each with different attributes. Horses must be tamed in the wild, stolen, or purchased in order to use them. The player can utilize trains and carriages for quick travel. The game's undeveloped land makes up the largest portion of the game world, featuring various rugged and vast landscapes with occasional travelers, bandits, and wildlife. Urban settlements range from isolated farmhouses to crowded towns. 
The player can witness and partake in random events as they explore the game world, including public hangings, ambushes, pleas for assistance, encounters with strangers, ride-by shootings, and dangerous animal attacks. Optional side activities are also available, such as dueling, bounty hunting, herb collecting, gambling, and hunting. Red Dead Redemption uses an Honor system, which measures how the player's actions are perceived in terms of morality. Morally positive deeds, such as capturing an outlaw alive or saving a stranger, will add up to the player's Honor. Conversely, negative choices such as murder will subtract from the player's Honor. This works in conjunction with the Fame system, which affects how non-player characters (NPCs) react to the player based on their Honor. If the player has high Honor, NPCs will greet them and they will receive discounts in some stores; if low, NPCs will act insecure and establishments may close their doors. The player can disguise themselves by wearing a bandana when performing criminal acts. 
Gunfights are an essential gameplay mechanic in Red Dead Redemption. The player can take cover, target a specific person or animal, blindfire, and free aim. Individual body parts can also be targeted, in order to take targets down non-lethally. Weapons consist of revolvers, pistols, rifles, shotguns, knives, explosives, and lassos. Aiming utilizes a gunslinger gameplay mechanic known as Dead Eye, a targeting system that allows the player to slow down time and mark targets. Once the targeting sequence ends, the player fires to all marked locations in extremely quick succession. The Dead Eye system upgrades and grants more abilities as the player progresses through the story. 
The game introduces the bounty system, a crime-governing mechanic inspired by Grand Theft Auto's wanted system. When the player commits a crime, witnesses run to the nearest police station. The player can either bribe or kill them before they reach the station, negating any consequences. Once the law is alerted, the Wanted meter appears with a bounty set on the player's head. The bounty grows higher as the player commits more crimes, and more lawmen will be sent to hunt them. After committing enough crime, the U.S. Marshals or Mexican Army will be sent to the player's location. To evade law enforcement in pursuit, the player must escape a circular zone or kill all lawmen in a town. If the player escapes, bounty hunters will continue to track after them. The bounty will remain on their head until they pay it at a telegraph station or present a pardon letter. 
The online multiplayer allows up to 16 players to engage in competitive and cooperative gameplay in a recreation of the single-player setting. Each game begins with a Mexican standoff, of which the survivors can move to any part of the battlefield in preparation for respawning enemies. Event types include deathmatch scenarios and capture the flag variants. Crates in the environment contain extra weapons, ammo, and other powerups. Players can level up and complete weapon challenges which earn them rewards such as new character models, golden weapon skins, new titles, and new breeds of animal mounts.[15] Multiplayer also features open-world gameplay, wherein players can form or join a group of up to eight players in a "posse" group and partake in hunting or attack other gangs or posses. In some game modes, players are unable to kill each other.