Twenty-One is a basketball game of skill practice. Most of the practice happens to be shooting baskets from the free-throw line. Three to five players are at a basket, and the rules are simple to follow. When a player makes a shot from somewhere on the court, he then goes to the free-throw line and shoots baskets until he misses. Another player would then get the missed shot rebound, and if he make a basket, that player then goes to shoot free throws.