Abstract Introduction Although it is possible to live well with dementia and many individuals with dementia lead active lives with the help of family, friends, and communities, the general impression of dementia is frequently negative. Dementia is a global health issue. Despite this, little research has been done on the effects of innovative dementia education strategies among undergraduate nursing students. The aim of this study was therefore to assess if this serious digital game, originally intended for the public, could increase knowledge about dementia in first-year nursing students. Methods The intervention was a digital serious game called “The Dementia Game”, which was available to students throughout February 2021, to a convenience sample of first-year undergraduate nursing students (n = 560) completing a BSc Honours Nursing Degree programme in one university in Northern Ireland. The game was evaluated using a pretest-posttest design. The questionnaire comprised of a 30- item true- false Alzheimer’s Disease Knowledge Scale (ADKS), which covers risk factors, assessment and diagnosis, symptoms, course, life impact, caregiving and treatment and management. Data were analysed using paired t-tests and descriptive statistics. Results Overall dementia knowledge increased significantly after playing the game. Pre-test to post-test increases were observed across a range of seven categories of dementia knowledge (life impact, risk factors, symptoms, treatment, assessment, caregiving and trajectory), with particularly large increases in knowledge of trajectory and risk factors, as shown using paired t-tests. All pre-test to post-test comparisons were significant at the p < 0.001 level. Conclusions A short serious digital game on dementia improved first-year student’s knowledge about dementia. Undergraduate students also expressed that this approach to dementia education was effective in improving their knowledge about the disease.