Through my PhD I am using neuroscientific techniques to celebrate the individual difference in video game players by creating adaptable systems that support personalised experiences and maximise user engagement. Specifically, I aim to make video games of all genres more accessible to all users, who may have different strengths or preferences in the games they consume. The primary mode in which I am doing this is through non-player companions (virtual agents that have a persistent presence in video games). I also aim to improve the foundation that Human-Computer Interaction (HCI) researchers use in their measurements and instruments by validating these against objective data and thorough user evaluation. Additionally, with experience in both 2D and AR interaction design in my undergraduate studies and research assistance roles, I hope to bring a unique perspective on the HCI field that benefits academia, the entertainment industry, and the end consumers.