Nowadays, there is an increased interest in using computer games for educational purposes. Educational computer games attempt to increase the students’ motivation and engagement. However, they should provide adaptivity to learners’ different needs and characteristics for better educational results. Towards this direction, this paper presents a novel adaptive educational game named FuzzEG, which teaches the knowledge domain of HTML programming language. It uses fuzzy sets to represent the learner’s knowledge level more realistically. Taking into consideration the learner’s progress, the game decides about the level of difficulty of the quizzes and whether the scenario is going to be dynamically expanded or not. The gain of this is that it provides the learner with a personalised learning and gaming experience. The game has been evaluated, and the results are very encouraging.