BlueTwelve co-founders Koola and Viv began working on Stray, originally known as HK_Project, as they wanted to pursue an independent project after working at Ubisoft. After they shared some footage from the game on Twitter, Annapurna Interactive reached out in April 2016 to publish the project.[3] BlueTwelve Studio was founded in 2016 for the development of the game.[4] Development took place in Montpellier in southern France. Stray was heavily influenced aesthetically by Kowloon Walled City, while the gameplay experience was specifically inspired by the founders' cats, Murtaugh and Riggs.[3] The development team found that gameplay as a cat led to interesting level design opportunities, particularly regarding platforming and puzzle elements.[1] The game utilises Unreal Engine 4.[5]