User interfaces that produce an immersive and intuitive in-game experience depend on a strong coupling between user input and the motion of game objects. Such user interfaces require a high sensitivity to user movement that has the potential to reveal characteristics of user cognitive processes that occur during gameplay. The current project investigates whether cognitive processing during deception affects in-game motion. We present here two paradigms that allow deception to be expressed over repeated trials and in a naturalistic setting. The first, an interactive exhibit at Science Gallery Dublin™, tracked motion while users deceptively responded to autobiographical statements. The second, a two-player bluffing game, tracked motion during unsanctioned, motivated deception. Our findings indicate that in-game motion is influenced by the cognitive processes underlying deception. In-game motion provides an important source of data on human psychological processes that can stimulate theoretical progress within psychology and contribute to the development of more credible artificial agents.