TT Games has shown how the Mayhem Collection changes LEGO Batman: Legacy of the Dark Knight when the villains take control. Joker and Harley Quinn receive a new story mission, a hideout beneath Amusement Mile and a repeatable mode built around fast runs through a locked-down part of Gotham. The expansion is not a simple character pack. It gives the pair a different rhythm, new ranged tools and a progression loop that turns the damage caused during each run into permanent additions to their base.
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Harleen Quinzel’s story begins inside Arkham
The opening mission follows Dr. Harleen Quinzel before she becomes Harley Quinn. Her first meeting with Joker unfolds inside Arkham Asylum, an area the main campaign only partly explores. TT Games presents the escape as a compact origin story rather than a copy of one film or comic. The sequence moves from an ordinary day in the institution to a loud breakout and a deliberately excessive farewell party.
The developers draw strongly from Batman: The Animated Series. Some scenes use a four-to-three frame as a visual reference to the television production, while details around Gotham point to several versions of Batman history. A shop called Sorkin’s Gems honours Arleen Sorkin, whose performance helped define Harley. These references sit inside the mission instead of replacing it, so a player who does not recognise every name can still follow the escape.
A hideout that records the player’s progress
After leaving Arkham, Joker and Harley move to Amusement Mile and establish a base below the Funhouse. The hideout is both a reward space and a practical record of progression. Players can open new areas, place themed props and change how the rooms look. That gives the expansion a clear home between missions and makes collected rewards visible rather than leaving every upgrade inside a menu.
Arkham inmates can also be rescued during trips into Gotham. A character called Henchmaster trains them, after which they can join a custom crew and be summoned in combat. The system fits the two villains because it turns a crowd of rescued troublemakers into part of their plan. More importantly, it gives players another choice before a run: personal upgrades improve Joker and Harley, while crew choices change the support available in a busy fight.
Mayhem Mode rewards movement, not careful policing
Mayhem Mode takes place across a restricted version of Gotham’s North Island. Each run has a time limit and a list of disruptive jobs: rob shops, break cash machines, paint graffiti, steal vehicles, fight ARGUS agents and collect studs. The goal is not to restore order. Players create as much useful chaos as possible, then carry the proceeds back to the Funhouse before starting another attempt.
Studs earned in the mode buy lasting improvements, hideout decorations and a set of new outfits. That structure lets a short run matter even when every optional task is not completed. A route through nearby shops may be better than crossing the island for one distant objective. The mode therefore asks players to read the street layout, keep moving and choose rewards that support the next attempt instead of trying to clear the entire map at once.
Joker and Harley fight from a different distance
The pair share some familiar abilities with the heroes, but their new gadgets put more emphasis on ranged attacks. They can move while using those tools, which supports a quicker run-and-gun style. That distinction matters because the timed mode regularly places several enemies between the player and the next target. Holding one position for too long wastes the clock and gives a larger group time to close in.
Group control is the practical centre of their combat design. A useful attack is not always the one with the largest immediate impact; it may be the gadget that opens a route to a vehicle or keeps agents away while studs are collected. The developers have not published a complete upgrade tree, so exact builds remain unknown. The footage and description do establish that mobility, range and crew support are intended to work together.
A focused expansion rather than a second main campaign
The Mayhem Collection does not replace Bruce Wayne’s campaign or turn the whole open world into a villain story. It adds a separate viewpoint with its own mission, base and repeatable activity. That boundary is useful. Joker and Harley can feel faster and less restrained without forcing every Batman objective to follow the same rules, while the shared Gotham still gives the expansion a strong connection to the base game.
TT Games plans to release the collection for Xbox Series consoles on September 18. The announcement confirms the main activities, permanent upgrades, crew feature and thirty new outfits, but it does not list every reward or the complete length of the story mission. Players now have enough information to understand the structure without treating the preview as a finished walkthrough.
