that the player had, such as a gun. Instead, they gave her helpful abilities such as tossing supplies to Booker or deciphering codes to connect her more emotionally to the player. She also served to help Irrational avoid tropes of the genre, such as receiving information over a radio or from someone on the opposite side of a window. Elizabeth's relationship to the Songbird was inspired by Levine's experience with a friend in an abusive relationship. Her design and costume was designed so players could recognize her from a distance given the open-space nature of the game and limited resolution, with the color scheme inspired by that of superheroes. For BioShock, the time period's advances in understanding DNA shaped the game's story of gene modifications. For Infinite, the same approach was used, with the game incorporating the development of quantum theory by Albert Einstein, Max Planck, and Werner Heisenberg that would later bore out in the Many Worlds Theory. Irrational consulted with physicist Mackenzie Van Camp to ground the game's science fiction in real quantum mechanics. Levine promised that the ending of Infinite was "like nothing you've experienced in a video game before", and wanted to avoid the issue from BioShock in which, after the death of Andrew Ryan before the last third of the game, the story lost its momentum. Technology and gameplay The team had to revolutionize their previous work on the BioShock game in order to realize Columbia, including both indoor and outdoor settings that take place thousands of feet above the ground. The modified Unreal Engine 2.5 used for BioShock was inadequate for their vision. Instead, they used Unreal Engine 3, modifying it with their own lighting engine and means to simulate the movement and buoyancy of the buildings. The development team found that the implementation of open spaces created new gameplay options for the player, such as deciding between long-ranged attacks or finding a means to move in for short-range or melee combat. The developers noticed that in BioShock, one players equipped specific plasmids and weapons, they could complete the game without having to alter their loadout. Irrational wanted instead to create situations through Infinites weapons and powers that would force players to change their tactics. The vertical and open-air spaces of Columbia provide more opportunity to include various types of combat compared to the close-ranged limits of Rapture within the first BioShock. The team