You have two sides.
One side is out in the field and one is in.
Each man that's in the side that goes in goes out and when he's out he come in and the next man goes in until he's out.
When they are all out the side that's out comes in and the side that's been in goes out and tries to get those coming in out.
When both sides have been in and out including not outs, that's the end of the game.
HOWZAT!