Can be played with 2 or more people. Pickup teems or "one" on "one" elimination. The manor you keep score is very flexible.
Use a tennis ball or similar, Standing in front of a stair case, (concrete works best) three or more steps high preferably. Throw the ball attempting to hit the corner edge of the step to get the most rebound. Bank shots on inside corner work well also.
Your opponent has to catch the ball on the fly and get 3 outs, then switch! You can set up bases or distances to determine 1st, 2nd & 3rd base hits.