Levels were designed in a fairly non-linear manner such that players can advantageously use air ducts, back doors, and sewers to avoid enemies or find hidden caches. These locations are also filled with objects with which the player can interact, that either benefit the player in some form, light switches make it easier to see, while water fountains and broken hydrants provide some health points or simply diversion, and tipping strippers provokes a quote from Duke, and a provocative reveal from the dancer.