Lego Batman 2: DC Super Heroes is an action-adventure open world game, and is in some ways similar to the Batman: Arkham series. The gameplay is similar to Lego Batman: The Videogame, and presented in the third-person perspective where the playable character is allowed access through the visible elements of the 3D space they are in, although some missions force the camera to be in a 2.5D perspective. The game is set primarily within Gotham City, although Metropolis is also visited as part of a mission. The player can freely explore Gotham City and unlock various characters within it, and some elements of Gotham City are broken into "bricks", which the player can use to build new suits or construct objects that can help solve puzzles.
Like its predecessor, the player can defeat enemies by using the abilities each character provides, such as Superman's super freeze or the Joker's handbuzzer, as well as traditional combat moves such as standard punches and kicks. Most enemies in the game don't carry weapons, although boss levels may have certain weapons or abilities that the player must counter. Combat rewards the player with studs, which the player can use to purchase new characters to use in the game's free roam section, and thereby contributes to their "True Hero" percentage for the mission. Some suits from Lego Batman: The Videogame return in Lego Batman 2, such as the magnetic suit for Robin, and the sonic, demolition and sonars suit for Batman. Certain adjustments exist between the two games, including the addition of a glass shattering gun to the glide suit (now called the bat suit), and the addition of a gun that can store water to the bio suit (now called the hazard suit). New suits available in Lego Batman 2 include the acrobat suit allowing for Robin to traverse areas that require acrobatics, magnet suit allowing for Robin to traverse areas with magnets and control magnetic elements, and ice suit to freeze water for Robin, and the sensor suit to go invisible and view X-rays, power suit to destroy silver objects and use super strength, and electricity suit to transfer energy between switches and move through areas with electricity for Batman.
The game takes approximately 15 hours to complete, with the main missions taking 9 hours and the various extras taking 6 hours. These extras take multiple forms. One such form is Citizen in Peril, where a citizen has put themself in a situation within the various missions where they must be saved by the hero. Another is each mission's gold bricks, which can be obtained through destroying certain objects, and a similar system exists with each mission's "minikits" wherein challenges must be completed in order to find them. Completing these various extras contributes to the total game's completion percentage.
Once a mission has been completed, it can be replayed at any time using the various characters that the player has unlocked in order to complete the aforementioned extras or to accrue more studs to purchase various characters.
A local multiplayer mode is also present using a split screen. The decision to use a split screen was due to the game's open-world environment. The Wii U version allows the use of the GamePad's screen instead of a split screen, allowing both players to have independent screens.
Unlike its predecessor, Lego Batman 2 features 75 playable characters from outside Gotham City, such as Superman and Wonder Woman. The Xbox 360 and PlayStation 3 versions of Lego Batman 2 feature exclusive downloadable content with two packs of characters, the Heroes Pack and the Villains Pack. Nightwing, Katana, Shazam, Zatanna, and Damian Wayne are playable in the Heroes Pack, while Bizarro, Captain Cold, Black Adam, Black Manta, and Gorilla Grodd are playable in the Villains Pack