According to the source, many senior members of Thief's team previously worked together at Ubisoft Montreal, and favoritism played a role in subsequent hiring practices, alienating fellow developers. High-ranking design roles saw an unusually quick turnover; some key members would leave the project less than two years after joining, and replacement designers would bog down the project by rebuilding or scrapping content.
Amidst office politics, the project was sidetracked by difficult-to-create press demos that strayed from initial concepts greenlit by publisher Square Enix. Polygon's source claims that Thief's production costs have inflated beyond initial estimates, and the project has changed so much over its development that content originally pitched to Square Enix no longer loads in the current build's heavily modified version of Unreal Engine 3.
Square Enix is expected to show off Thief at E3 in June.