This game is damn fantastic, hilarious, but like all action games, this game suffers from badly defects.
Within the open world, the player can use a map and the Deuce's turn signals to guide them towards either story-advancing missions or side missions. Side missions include hot-rod races against a demon, defending Eddie's allies from a pending attack, or helping a cannon operator spot his targets. There are about 23 main missions in the story with 30 side missions that the player can optionally take. The player can also explore the game's world to find statues bound in leather or chains that can be freed to gain a health boost for Eddie or to reveal part of the game's backstory, and can look through special telescopes at vistas or complete certain jumps to earn additional Fire Tributes. The player can also find monuments they can raise that unlock an additional heavy metal song from the game's soundtrack that can be played on the Deuce's radio, "The Mouth of Metal"; the player can further customize its set list with songs they have been rewarded with or have collected.
The single-player and multiplayer modes of Brütal Legend feature Stage Battles where players command armies to defend their concert stage while attacking others' stages.
Several main story missions of the game are Stage Battles based on real time strategy elements. The player, while still in control of Eddie, is required to defend a giant stage where new allies will spawn, holding out until a specific objective is completed. The player creates an army for attacks by building merchandise booths on "fan geysers" through Clementine's magic. Once enough fans are collected, the player can summon different allies, each consuming a specific number of fans, or upgrade their stage to allow them to produce more powerful allies. A character known as Mangus acts as the "sound guy" to help in the construction of these units and stage upgrades, and also warns the player of enemy attacks. Once the player has gathered their army, they can then seek out and attack their opponents. Eddie is able to control the entire army to follow, attack, or defend a point, and can use specialized squads of specific units to perform certain tasks, such as having a group of headbangers use their headbanging to destroy statues. The player can also use Eddie directly in combat during this battles. Ultimately, Eddie transforms into a winged demon who can fly above the battlefields to issue orders or lay out attacks. Other spells in Eddie's arsenal can help control the performance of his armies, such as temporarily boosting their attack skills or creating a rally flag which troops will gather at. Each of the different units, including special allies that Eddie meets in the game, has a special co-op move they can perform with Eddie; for example, Eddie's first ally, Ophelia, can be tossed at foes by Eddie in the style of the Fastball Special. These co-op moves are also available outside of Stage Battle missions.
The game has a multiplayer mode, described by Schafer as "your typical head-to-head, battle of the bands scenario. But with axes." The multiplayer modes are team-based and play in the same manner as the single-player Stage Battles, with team sizes from one-versus-one to four-versus-four. Each team selects from one of three factions which affect what resources and troops they can summon, and are tasked with defending their stage from attack by the other team. The three factions available are Ironheade, mostly human-based troops led by Eddie Riggs; The Drowning Doom, with more Goth/Black Metal creatures led by Ophelia; and The Tainted Coil, evil creatures controlled by Doviculus. Each player controls a single main avatar who has the same abilities as in the main game for combat and magic spells and can also fly about the map, but also is in control of troops that they may summon from the team's shared resources-fans as generated by fan geysers across the map. Different types of troops are available, costing various amounts of fans to summon, with the potential to upgrade to improved units through different routes. The number and types of troops that can be summoned is limited by a cap to prevent either team from becoming too overpowered. All of the troops can be engaged by the player to initiate various "Double Team" moves as with the single player game. The game can also be played by a single player with computer-controller opponents at one of five difficulty levels.