 Looking Glass Studios began designing Thief II in January 1999 . The team 's goal was to build on the foundation of Thief : The Dark Project , a game that Thief II project director Steve Pearsall later said was an experiment . He explained that the team had played it safe by including certain " exploration ... or adventure oriented " missions with " jumping and climbing puzzles " in Thief , and that the new game was significantly more focused on stealth . Combat was given less prominence than in the original . Based on feedback from players and reviewers of Thief , the team decided to scale back the use of maze @-@ like levels and monsters such as zombies in favor of urban environments and human enemies . Pearsall stated that Thief 's monsters were negatively received because , unlike the game 's human enemies , they did not clearly indicate when they noticed the player . The team sought to remedy this problem by improving the audio cues given by non @-@ human enemies in the sequel . 
