This work is conducted at two levels to meet the requirements of this research. The first objective is to develop a better understanding of how to design better sound-only games for a wide range of users. A new theoretical framework has been crafted to achieve this objective (Human Understanding Theory of Novel Games with Simplex, or the HUNGS theory). Such a theory aims to capture the current consensus about user requirements (as far as it is possible to do so) whilst understanding the principles and practices of interactive systems, namely the design of accessible sound-only games. The second objective is to understand better the psychology of intended users of such games. The importance of the present work is to test psychological concepts in the very different and very popular context of computer games. Implications found for users at work or working on serious tasks may not generalize to game players. To achieve the second requirement, a number of existing games were explored before a new game was designed (namely the Totally Lost game), using a range of methods. The Totally Lost game and different versions of the same game have been designed and evaluated based on user experiences.