Although educational games have been used for a considerable time, their true potential for enhancing achievement and motivation is still being explored. We argue in this paper that we may get closer to realizing this potential if the theoretical underpinning of educational games is improved. We developed a simple interactive math game based on insights from cognitive load and game design theory, in which players solve mathematical problems competitively and creatively. To investigate the effects of the game on achievement and motivation, we ran an experiment with fifth- and sixth-grade students. Our results show that students who played the game achieved better math results than those who did not. We did not find any significant differences in math motivation. Another promising finding, albeit beyond the scope of our hypotheses, relates to the potential effects of math games on student behavior.