Test Subject Incomplete is a puzzle-platform game released on April 1, 2013. The game was originally intended to be the third and final installment of the Test Subject trilogy, wrapping up a series that started in 2011. However, nearing the end of production Nitrome realised that three installments was too little space to delve in detail into the complex universe of Test Subject. As such, with a fourth installment, Test Subject trilogy will become the Test Subject cycle.