Brawlhalla is a free-to-play platform fighting game developed by Blue Mammoth Games. It was originally released for macOS, PlayStation 4 and Windows in 2017, with ports for Nintendo Switch, Xbox One, Android and iOS released later. Full cross-play is supported across all platforms. The game was shown at PAX East in April 2014 and went into alpha later that month. An open beta became available in November 2015, followed by the game's full release in October 2017. The game features 66 playable characters, referred to as "Legends", each with unique stats, varied loadouts, and cosmetic skins and crossovers.

On March 5, 2018, Brawlhalla developer-publisher Blue Mammoth Games was acquired by the video game publisher Ubisoft. As a result of this, Ubisoft took over publishing duties and Rayman, alongside two other characters from the franchise, were added to the game on November 6, 2018. Brawlhalla was released for Nintendo Switch and Xbox One on the same day. On July 27, 2022, Ezio from Assassin's Creed became the second playable crossover character, alongside one other character from the franchise.

On July 6, 2018, Ars Technica released an article detailing precise player counts for Steam games obtained through a leak as a result of a "hole" in its API. This leak showed Brawlhalla to be ranked 24th in player count on Steam with a total of 8,646,824 players, out of all games featuring the Steam Achievements system. The Android version has more than 10 million downloads. Ubisoft reported more than 20 million players by February 2019. In April 2022, Brawlhalla achieved 80 million players.

In most of Brawlhalla's game modes, the goal is to knock one's opponent into one of four areas outside of the visual boundaries of the map referred to as blastzones, similar to Super Smash Bros. This can be done either by forcing them into one of the blastzones with an attack, or by preventing them from returning to stage and allowing gravity to force them into the bottom blastzone. Damage can be seen on the color display around each player's character icon, which darkens progressively from white to red to black as the character continues to get hit. The darker the color is, the farther the character will be knocked back when hit until a hit forces them into a blastzone. Entering a blastzone will result in the player losing a stock and their character respawning on stage. Either the last player with at least one stock or the player with the most points wins the match, depending on the game mode.

The game supports both local and online play. Competitive players can compete in 1-on-1 to climb through the rankings. They can also find a partner to play against other duos to increase their collaborative rank in either the standard stock game mode queue or a rotating queue that features a different game mode each season. Brawlhalla also has several casual modes: Free-For-All, 1v1 Strikeout, Experimental 1v1, and a different featured mode every week. Free-For-All is a chaotic mode where 4 players knock each other out to gain points. In 1v1 Strikeout, players pick 3 characters which they play for 1 stock each. Experimental 1v1 allows players to test out upcoming features against each other. Custom games can be hosted online and locally, and they support up to 8 players per match, experimental maps, and region changing. You may join groups of your friends to create a clan, with multiple ranks within the clans. Clans are only available on PC. Clans gain experience from all members.

Brawlhalla features simple controls and one-button special moves. This allows new players to pick up the game quickly. Controls include movement keys and buttons for attacking, performing special moves, picking up or throwing weapons, and dodging. Keys can be rebound for the keyboard and a large variety of controllers.

Players can move by running left and right and jumping. Players can perform quick dashes sideways on the ground and dodges in the air or on the ground, either sideways or vertically. It is also possible to dodge right after an attack to keep pressure on the opponent. Once in the air, the player has the option to perform any combination of three jumps, a directional air-dodge, a grounded move in the air by using a "gravity-cancel", and "fast-falling". It is also possible to hold on to the sides of stages, similar to the style in Mega Man X.

During a match, gadgets (which can be switched off in the ranked game modes) and weapon drops fall from the sky semi-randomly and can be picked up by the players. Although the weapon drop sprite has the appearance of a sword it turns into a corresponding weapon for the legend that picks it up. All of Brawlhalla's characters can use 2 weapons out of 15 to fight each other. Weapons include blasters, katars, rocket lance, sword, spear, cannon, axe, gauntlets, hammer, bow, scythe, orb, greatsword, battle boots, and chakram. Blasters, rocket lances, bows, and spears perform well at a distance from the opponent, while katars and gauntlets are more effective up close. Rocket lance allows for quick traversal of the stage. Cannon, greatsword, and hammer all do large amounts of damage. Sword, orb, katars and battle boots are fast and low damaging. As chakram also does well at a distance, unlike others, it can split into two if the user holds down and attacks. All characters have unarmed attacks, should they be disarmed. Gadgets like bombs, mines, and spike balls are also used. Weapons can also be thrown to interrupt the enemy's moves or to make it difficult for them to get back to the stage. Each character has 3 special or "signature" moves per weapon, for a total of 6 per character.