Uncertainty may be an important component of the motivation provided by learning games, especially when associated with gaming rather than learning. Three studies are reported that explore the influence of gaming uncertainty on engagement with computer-based learning games. In the first study, children (10-11 years) played a simple maths quiz. Participants chose their preferred reward for a correct answer prior to seeing each question. They could either receive a single point or toss an animated coin to receive 2 points for heads or none for tails. A preference for the uncertain option was revealed and this increased during the quiz. The second study explored the discourse around learning when pairs of participants (13-14 years) competed against the computer in a science quiz. Progress depended on the acquisition of facts but also on the outcomes of throwing dice. Discourse was characterised by a close intermingling of learning and gaming talk without salient problematic constructions regarding fairness when losing points due to gaming uncertainty. A final experiment explored whether, in this type of game, the uncertainty provided by the gaming component could influence players' affective response to the learning component. Electrodermal activity (EDA) of 16 adults was measured while they played the quiz with and without the element of chance provided by the dice. Results showed EDA when answering questions was increased by inclusion of gaming uncertainty. Findings are discussed in terms of the potential benefits of combining gaming uncertainty with learning and directions for further research in this area are outlined.