In each inning, players take turns at the plate and on the mound. When batting, you get hits and can move your runners by correctly guessing the base where the pitcher has hidden the baseball. If the ball was hidden at second base and you find it, you hit a double and can move your runners two bases.
When pitching, keep the batter from reaching base and scoring runs by fooling them three times. Each incorrect guess is an out. The player with the most runs at the end of the game wins!
—description from the designer