Tomb Raider: Underworld is an action-adventure video game developed by Crystal Dynamics and published by Eidos Interactive for Windows, PlayStation 3, Xbox 360, Wii and Nintendo DS in November 2008. Later versions were released for mobile in December 2008, PlayStation 2 in 2009, and OS X in 2012. Various companies ported or developed the different versions. The ninth overall entry in the Tomb Raider series and third in the Legend trilogy, Underworld follows archaeologist-adventurer Lara Croft as she searches for Mjolnir, an artefact key to entering the realm of Helheim, while confronting adversaries from her past. Gameplay features Lara navigating levels set across the world through platforming, fighting enemies and solving puzzles to progress.