Acute cognitive benefits, such as temporary improvements in concentration, can result from as few as ten minutes of exercise; however, most people do not take exercise breaks throughout the day. To motivate people to receive the cognitive benefits of exercising in short bursts multiple times per day, we designed an engaging casual exergame. To determine whether there are cognitive benefits after playing our game, we conducted two studies to compare playing ten minutes of our casual exergame to a sedentary version of the game or exercise on a treadmill. We found acute cognitive benefits of the casual exergame over the sedentary version (but not treadmill exercise), demonstrated by significantly improved performance on two cognitive tests that require focus and concentration. Significant improvements were also found in participants' affective states after playing the casual exergame. Finally, our casual exergame produces similar exertion levels to treadmill exercise, but is perceived as more fun.