This article describes the expectations and experiences of young (16 to 19 year old) digital game jam participants (N = 34) who attend Finnish general upper secondary schools. Game jams are a form of game creation: events where games are made in co-operation. They are widely used in game design education and in addition, when participated voluntarily, learning has been reported as an important motivation. The existing literature mostly concentrates on game jams for adults, and informal or non-formal learning. This article is adding to the literature by examining learning in formal education for adolescents. As part of our research, we have organised game jams in formal general education, and this article is based on the pre-event and post-event surveys of three game jam events. The article maps 1) the motivations to attend a school related game jam, 2) the expectations and apprehensions the would-be participants have, 3) what kind of learning game jams promote, and 4) how does attending a game jam affect participants' attitudes and apprehensions regarding learning, STEAM and information technology, and their own skills. Our results indicate the creative side of digital game making, desire to learn new skills and make new friends to be the main motivations for participation, and the lack of confidence in technical skills to cause most anxiety before the jam event. The effects of attending a game jam are mostly positive, with the participants reporting learning experiences in several soft and technical skills and increased motivation to take part in creative and co-creative projects. A gendered result can be seen in the participants' altered stance on technology and programming: girls and non-binary students report technology and programming being easier and more fun than they had thought before attending a game jam event, which is well in line with previous research on STEM/STEAM education and gender.