This paper offers an insight into the games software development process from a time perspective by drawing on an in-depth study in a games development organization. The wider market for computer games now exceeds the annual global revenues of cinema. We have, however, only a limited scholarly understanding of how games studios produce games. Games projects require particular attention because their context is unique. Drawing on a case study, the paper offers a theoretical conceptualization of the development process of creative software, such as games software. We found that the process, as constituted by the interactions of developers, oscillates between two modes of practice: routinized and improvised, which sediment and flux the working rhythms in the context. This paper argues that while we may predeterminately lay down the broad stages of creative software development, the activities that constitute each stage, and the transition criteria from one to the next, may be left to the actors in the moment, to the temporality of the situation as it emerges. If all development activities are predefined, as advocated in various process models, this may leave little room for opportunity and the creative fruits that flow from opportunity, such as enhanced features, aesthetics and learning.