The cloud computing paradigm promises to provide flexible IT services delivered via the internet. The cost efficiency of cloud computing services is mainly enabled by a high degree of automation realized by SLAs and minor direct human interaction. In this paper, the authors analyze eight expert interviews to identify and discuss the different levels of trust from an end-user perspective (trust in mediator and provider) that are prevalent in cloud computing and the main drivers influencing trust. Then, they use the findings to postulate hypotheses that they subsequently verify by means of a serious game. They discover risk aversion, information, disposition of trust, affectedness, reputation and costs to be important factors influencing trust in cloud computing mediators or providers, respectively.