The goal of this thesis was to evaluate the Unreal Development Kit (UDK)as an evolutionary game prototyping tool. To conduct this evaluation in arealistic setting, a prototype of a game concept was to be implemented usingthis tool.To aid the prototyping process, extensive research was done into existing theoryon game prototyping, as well as how traditional prototyping techniques can beutilized in a game prototyping environment.The project team created their own prototyping process tailored for evolutionarygame prototyping, based on the theoretical insight gained through theresearch on general prototyping processes. Due to time constraints, the teamwas unable to test this process extensively. This is work that remains beforethe process can be fully recommended for further use.During the evaluation process, the team identified key criteria for evaluatinga game prototyping tool and compiled this into an evaluation framework. Thekey points identified in the evaluation was that the UDK offers low-risk licensingterms for a game engine suite with an outstanding track-record of successfulgame titles. To properly utilize the speed gains that can be achieved throughthe UDK, a deep understanding is needed of its feature set.The main challenge in this project was the balancing act of two somewhatconflicting goals: Acquiring knowledge of the UDK, thus covering the breadthof its features, while at the same time following narrowly focused prototypingtechniques.From this work, the project team has gained deep insight into one of the gameindustry’s most widely used engines and how it can be used as an evolutionaryprototyping tool. The team is particularly satisfied with the evaluationframework and the evaluation itself, as these will provide useful informationfor anyone considering using the UDK, both professionally and academically.Engine developers will also benefit from a novice user’s point of view.