League of Legends is a multiplayer online battle arena where players control a "champion"[6] in order to be matched in a short PvP battle or bot game. As of February 27, 2014, there are 118 different Champions from which to choose. Players gain levels from killing the opposing team's Champions, controlled by other players or bots, and minions that regularly spawn and attack the other team's turrets, minions, and champions. In the classic game mode, the map is typically divided into "lanes", which are paths that spawned minions take, the "jungle", an area between lanes where neutral monsters spawn, and "bases", where players spawn and can purchase items. The primary map, Summoner's Rift, features three lanes, commonly referred to as top lane, where bruisers (partially damage, partially tanky) and tank type champions tend to go. Mid lane, where assassins and burst damage carries tend to go, and bot lane, where the ranged DPS (damage per second) carries and their supports tend to go. The jungle is sometimes considered a lane, where an assassin or tank champion tends to roam in order to collect buffs and assist in the other lanes freely. The player earns a small amount of gold every second passively, but can earn more by getting the last hit on minions, destroying enemy towers (referred to as turrets) that guard the lanes, neutral monsters located in the jungle, and killing enemy champions. With this gold, users can buy a variety of items to strengthen their champion for the duration of the game. On the classic Summoners Rift, Twisted Treeline, and Howling Abyss maps, the game is ended by destroying the enemy team's last structure on the map, called the "Nexus", from which minions spawn. Other maps have variations of rules and objectives, such as Dominion on the Crystal Scar map, where each team's Nexus loses health if the opposing team controls at least three of the five towers located around the map.[7]

The player is identified as a "Summoner" and acts as the persistent element in the game, to be used to track statistics and scores for each player.[8][9] Summoners gain experience points and "Influence Points" (in-game currency) for each battle they participate in. Experience points lead to persistent level gains for the Summoner, up to a maximum level of 30. The benefit of gaining levels is unlocking Mastery Points and Rune Page slots (below) which improve the overall strength of the Summoner's chosen champion in-game. The Summoner can also choose two summoner spells.[8] These spells significantly impact gameplay, and have a high cooldown while costing no mana. All spells can be improved by masteries (perks that affect gameplay), which are developed in a skill tree.[8] All of the masteries are passive effects, although some augment items which can be activated. They are grouped into Offensive, Defensive, and Utility categories. Masteries can be re-distributed at will between battles.

Champions Quinn and Jinx (bottom) face off against Taric (top) in the bottom lane of Summoner's Rift.
Similar to masteries, runes affect gameplay in minor ways. Runes are categorized into Marks (offensive), Seals (defensive), Glyphs (magic) and Quintessences (utility). They must be unlocked in the Store; it is possible to own multiple copies of one rune. Summoners must arrange their runes in the Runebook to benefit from them. The Runebook has limited number of slots for each rune type, but more rune pages can be purchased from either Influence Points or Riot Points. Combining two equal-tier runes produces a random rune of the same tier, while combining 5 equal-tier runes produces a higher-tier rune.

The League of Legends Store allows players to purchase additional options through Riot Points (RP) and Influence Points (IP). Riot Points must be bought using real money, while Influence Points are earned by playing the game.

Moderation is conducted through a democratic system known as The Tribunal. In this system, player-submitted reports are reviewed by other players on a case-by-case basis. The reviewing players then submit their opinions on the legality of the behavior demonstrated. A consensus renders the decision official. It is notable that players are unable to be permanently banned through this system, since "all permanent bans are distributed manually." Reviewers receive a Justice Rating based on their accuracy to encourage thorough analysis of cases.[10]

Game modes and matchmaking
League of Legends is a session-based game. Matchmaking creates teams with even average MMR (Matchmaking Rating) of the constituent players. MMR uses the Elo formula with proprietary adjustments.[11]

Tutorial mode is a set of two introductory sessions that teach the basics of the game. It is intended to help new players learn concepts such as the controls and the game's HUD.
Custom mode allows players to create games that players manually join rather than relying on the game's matchmaking system to create the teams. In custom matches, the teams can be uneven and may include a mix of players and bots, which are computer-controlled champions.
Classic mode is a normal or ranked match played either 5v5 on Summoner's Rift - a three-lane map with each team's side having three lane turrets and an inhibitor per lane, as well as two base turrets and a nexus - or 3v3 on Twisted Treeline - a two-lane map with each team's side having two lane turrets and an inhibitor per lane, as well as one base turret and a nexus. The map also has three altars, two of which add bonuses to the players, and the third heals the players, these altars are surrounded by a jungle. A team wins by destroying the enemy team's nexus, which can only be attacked if all lane turrets and the inhibitor in at least one lane and all base turrets are destroyed.
Normal matches are Player versus player. Blind Pick matches allow both teams to pick champions at the same time, but each team does not learn what the opposing team has picked until all picks have been finalized; players may therefore incidentally choose the same champion as a player on the opposing team, but players may not choose the same champion as another player on their own team. Draft Pick randomly assigns a team captain for each team, who then take turns banning three champions each, disallowing both teams from playing those six champions. Draft players then choose their champions in an ordered back-and-forth format. Because both teams can see which champion each player is picking, no player can pick a champion that has already been picked by another player.
Ranked matches are available to players that are level 30. Ranked uses the Draft Pick system exclusively, and players are seeded into a League system based on the outcome of their matches. Winning and losing games influences a player's MMR, which is intended to keep all players' skill levels in any given game as close as possible.
Co-op vs. AI mode matches players against a team of bots. Similar to the Tutorial mode, it is also intended mainly as a way for inexperienced players to learn.
Dominion mode is a normal match played 5v5 on Crystal Scar - a map with a single circular lane that has five neutral turrets arranged in a star pattern. A team wins by reducing the life total of the enemy team's nexus, which only occurs if the opposing team controls at least three of the five neutral turrets, until it is zero.
ARAM (All Random All Mid) mode randomly picks champions that the players are able to play, allowing up to 2 re-rolls if the player is unsatisfied with their pick; players may also trade with teammates if both parties own the champions to be traded. The mode is played 5v5 on Howling Abyss - a one-lane map with each team's side having two lane turrets, an inhibitor, two base turrets, and a nexus. A team wins by destroying the enemy team's nexus, which can only be attacked if both lane turrets, the inhibitor, and both base turrets are destroyed.
One for All was the first limited time game mode, which was available during the 2013 Harrowing. In One for All, the game randomly assigns a team captain for each team, who then take turns banning three champions each, disallowing both teams from playing those six champions, as with Draft Pick. Players on each team then would select champions at the same time. Each player is only aware of their own team's choices until all picks are finalized, as with Blind Pick. However, unlike in Blind Pick or Draft Pick, there is no restriction on choosing a champion that has already been picked. Once all players have chosen, each team is assigned the champion that was picked by the most players on that team (in the event of a tie, the game breaks the tie at random), and all players had to play as this champion. One for All could be played 5v5 on either Summoner's Rift or Howling Abyss.
Showdown was the second limited time game mode, available during the 2013 Snowdown Showdown. Each team played until one team achieved one of three goals: taking down an enemy turret, reaching 100 team minion kills, or killing the enemy player (two kills are necessary in 2v2). Showdown is played either 1v1 or 2v2 on Howling Abyss.
Hexakill is the third limited time game mode. Taking place on Summoners Rift, each team has six players instead of the typical five.
Ultra Rapid Fire mode was introduced on April 1, 2014 as the fourth limited time game mode. It is a Classic Draft game, except that all champions have their movement speed increased and gain gold quicker, abilities do not cost any mana or energy to use and have 80% faster cooldowns, ranged attacks deliver 25% more damage on critical hits, among other changes. Several champions are unavailable in this mode.