This research explored the perceptions that postgraduate students have of a compulsory subject within a master's degree from a Spanish online university, when using Quizizz. A mixed methodology is used where the qualitative analysis traces the roadmap for the quantitative one, identifying the key themes revealed by a sample of 11 students, which were then used to build a survey launched to 106 students. The conclusions are: firstly, Quizizz can maintain the curiosity and attention of the students, improve participation and motivation in the virtual classroom and generate pleasant learning experiences; second, students perceived Quizizz as an engaging and fun platform; third, competitiveness emerged as an important variable driving students' intrinsic motivation, driven by the desire to be among the top ranks in game rankings; and fourth, Quizizz is a valuable tool for reviewing and retaining key concepts and ideas, but not necessarily for improving test scores. Finally, Quizizz has a positive influence over motivation, engagement, and dynamization of the virtual classroom.