What do math and monsters have in common? Both can be scary! But they can be fun too. Mathemarmite offers young children an opportunity to hone their counting abilities in a cosy, timeless and friendly environment where they can follow various recipes and mix specific ingredients in the right quantities in a cauldron to cast spells and discover a variety of monstrous transformations that they can immortalize in their Monster Photobook. Mathemarmite, however, is not only a game—it is also a research project conducted by the xCIT research group at the University of Luxembourg in collaboration with experts in children’s mathematical abilities and machine learning. Data gathered as people play the game is used to personalize in real-time the individual's learning experience but is also processed extensively offline to improve our understanding of the human mind. Knowledge gained with the data collected in this game will be used to improve the game and hopefully learning in subsequent iterations. By playing Mathemarmite we hope that your child will have fun with math and contribute to the development of better educational games for future generations.