Spy game Operation Math ($3) turns kids ages 5 to 12 into secret agents battling Dr. Odd, who's on a global quest to eliminate the world's even numbers. Kids can thwart his plans by completing addition, subtraction, multiplication, and division equations. This game is all about beating the clock, so start in training mode, which allows your kids more time to think through answers. Players will love getting new uniforms and spy gear for each mission completed.