Game design is a complicated, multifaceted creative process. While there are tools for developing computer games, tools that could assist with more abstract creative parts of the process are underrepresented in the domain. One of such parts is the generation of game ideas. Ideation (idea generation) is researched by the computational creativity community in the contexts of design, story and poetry generation, music, and others. Some of the existing techniques can be applied to ideation for games. The process of generating ideas was investigated by applying said techniques to actual themes from game jams. The possibility of using metaphors produced by Metaphor Magnet together with ConceptNet was tested and the results are presented as well. Vain tiivistelmä. Opinnäytteiden arkistokappaleet ovat luettavissa Helsingin yliopiston kirjastossa. Hae HELKA-tietokannasta (http://www.helsinki.fi/helka/index.htm). Abstract only. The paper copy of the whole thesis is available for reading room use at the Helsinki University Library. Search HELKA online catalog (http://www.helsinki.fi/helka/index.htm). Endast avhandlingens sammandrag. Pappersexemplaret av hela avhandlingen finns för läsesalsbruk i Helsingfors universitets bibliotek. Sök i HELKA-databasen (http://www.helsinki.fi/helka/index.htm).