This dissertation presents three years of research on how design processes in game jams and hackathons can be understood as accelerated. Hackathons and game jams can both be described as formats where participants engage in designing and developing prototypes during an intentionally short time frame, such as 48 hours, which is meant to facilitate creativity, and encourage fast decision making and rapid prototyping. Game jams and hackathons are organised in many different contexts and for many different purposes as well, such as: internally in companies to spark new ideas; for fostering citizen innovation for municipalities; in cultural and governmental agencies; integral parts of education; entry points for developers wanting to enter especially the game industry (Olesen, 2020; Kultima, 2015). During the recent decade, game jams and hackathons have been introduced to academia as well, as formats for teaching and learning, and as research platforms as well. Only few research contributions engage with understanding how accelerated design processes in game jams and hackathons unfold, or how the organisation of game jam and hackathon formats influence these accelerated design processes. The main contributions of my PhD project are: 1) Descriptive process-level knowledge, which contextualise and solidify how accelerated design processes unfold under the circumstances of a game jam and a hackathon. 2) Overviews of how game jams have been organised for supporting participants' creativity and of how hackathons have been used as means and as research focus within academia. 3) Exploring how game jam and hackathon formats may be organised in order to support knowledge generation such as within academia, and in order to support creativity.