Tomb Raider: Underworld is one of two mobile games that are based on the PC/console game with the same name. Both games feature the same plot. It starts in Baldr's tomb where Lara's task is to find Thor's helve. The player has to explore the tomb and find a key to the crypt. By following the trail of Thor's artifacts Lara hopes to be able to get to Avalon where she thinks her mother might be. This version of the game is a side-scrolling 2D platformer.