To achieve 100% completion in "Free Play" mode, you must unlock specific characters with unique abilities to interact with the environment:
: Costs 500,000 studs. Useful for Shattering glass (Sonar) and flight. Technical Note on the "RELOADED" Release
: Costs 125,000 studs. Used to open Riddler Boxes .
: It was the first LEGO game to feature an open-world environment (Gotham City) and full voice acting for the characters.