The big picture
Does gamification work?
Gamification is using game design elements outside games. Average effects are small to moderate and depend heavily on context and design.
ContestedReplications or meta-analyses disagree. Do not assume the effect.
Example
The same badges and leaderboards can increase persistence in one setting and lower satisfaction and grades in a classroom.
Why it works
Outcomes depend less on the element than on how people read it. Read as feedback on mastery, it raises motivation. Read as control or comparison, it lowers it.
On the web
Do not assume gamification lifts results. Decide which behavior and metric to move first, then pick elements. In A/B tests, measure both the main metric and a guardrail.
When it backfires
Do not judge from the launch week alone. Novelty can move numbers briefly, so check the trend over several weeks.
Sources
Defines gamification as the use of game design elements in non-game contexts.
Deterding, S., Dixon, D., Khaled, R., & Nacke, L. (2011). From game design elements to gamefulness: Defining "gamification". MindTrek 2011, 9-15. Open source
Most of 24 empirical studies reported positive effects, but results varied with context and users.
Hamari, J., Koivisto, J., & Sarsa, H. (2014). Does gamification work? A literature review of empirical studies on gamification. HICSS 2014, 3025-3034. Open source
Effects on learning were g = 0.49 for cognitive, 0.36 for motivational, and 0.25 for behavioral outcomes. Only the cognitive effect held in methodologically rigorous studies.
Sailer, M., & Homner, L. (2020). The gamification of learning: A meta-analysis. Educational Psychology Review, 32, 77-112. Open source
A course with badges and a leaderboard showed lower intrinsic motivation, satisfaction, and final exam scores than a course without them. It is a single-course study.
Hanus, M. D., & Fox, J. (2015). Assessing the effects of gamification in the classroom. Computers & Education, 80, 152-161. Open source