Summarize this article in one sentence.
Research sports that you know of. See how they are played, what the rules are, how you win, and what penalties there are. By learning about lots of sports, you are able to see what you like and dislike.  Start a list of features from various sports that you want your sport to include. You might take the layout of a baseball field, the play features of bocce ball, and the penalties of football. Don’t take more than one or two features from each sport unless you want to create something that’s a variation of a sport that already exists. Write out how the game is played and how a winner is determined. Be as specific as possible about what each player or team must do and what they are not allowed to do. Decide if there is a time limit or if play goes on until a certain score or goal is reached.  Decide if teams rotate turns or if play shifts back and forth between them at random. For example, in volleyball, each team serves at specific times, but play passes back and forth until one team misses the ball. In baseball, teams take turns being at bat and in the field. Many sports, like soccer, have a time limit and the winner is whoever has the most points. Others, like tennis, are played until a specific point value is reached. If you want the sport to require teams, decide if there must be a set number or if it can vary. On the other side, plan the sport differently if you want it to be a one-on-one game. Keep in mind that some of the most popular sports are adaptable for a range of players.  Sports like soccer, basketball, ultimate frisbee, and football are designed to accommodate a range of player numbers. They typically require at least two people per team and up to ten or eleven, but the game can be played with any number in between. Games like ping pong, tennis, and racquetball require at least two and no more than four, in most cases. Set out what you think is the ideal number of players, but make note of how the game could be adapted for different numbers of players. Start broad, and expand outward into specifics. Make sure there are enough rules to make the sport work but not so many that it becomes confusing for players to learn it. For starters, set out five to ten basic rules.  You might brainstorm lots of rules and then rank them in terms of importance. Go through a process of elimination to get rid of ones that are not necessary. Rules include what players must do, what they are allowed to do, and what they are not allowed to do. For example, players must walk, are allowed to jump, but can’t run. Incorporate various rules from sports that already exist, which you researched in the first stage of the sport’s development.

Summary:
Browse the rules and objectives of existing sports. Outline the basic objective of the sport. Determine the ideal number of players. Write out all of the rules that are necessary to make the game work.