Red Rover is a somewhat violent game commonly played in schools where the teachers are either sadistic or indifferent to the well-being of their students. Regardless, it can be great fun, assuming no-one is seriously injured in the process of the game. Advanced players may wish to wear padding.
What you need
20+ gullible and/or masochistic players.
A medium-sized field, say 20 metres or more on a side.
Divide all the players into two teams, using the method of your choice. These two teams should form two lines, facing off at a distance sufficient to get a good sprint going, but not so far as to induce cardiac arrest before reaching the other side. The players join hands with the two people next to them1, to form an unbroken 'wall.' Decide which team goes first.
The team that is going first decides amongst themselves a player on the opposite side to call. Once a decision is reached, the team shouts in unison the following rhyme2:
'Red Rover, Red Rover, Send [person's name] on over!'
At which point the selected individual must break ranks and charge across the field as fast as they can. Assuming this individual is you, your task is to run at full speed into the clasped hands of one pair of people on the opposing team, with the intention of breaking their grip and penetrating the line. If you are successful, then you may select one of the people whose grasp you broke, and have them join your team. You both return to your original side, and rejoin the wall. If you fail and are stopped without breaking through the wall, then you must join the other team's wall and play for them. A small break may be allotted (or be essential) to recover from any injuries any parties have suffered in this exchange.
Play continues, with alternating sides calling players, until only one player is left on one side, and is thus unable to form a wall.
Red Rover is, as mentioned, an inherently violent game. As a precaution against more severe injuries, it is generally advisable to limit what sort of grip the players may use when linking hands, and what position they may hold their arms in. A typical fingers-wrapped grip is best, with the stipulation that the elbows may not be bent to raise the hands upwards, which both greatly increases the strength of the link, and also presents a projecting fist for the runner to smash into - a nasty set of circumstances as you might imagine, not many people like running full-speed into the joined fists of two other people with their stomach.
There are several variations on the game Red Rover, mostly involving what happens when a runner breaks through the line. In one version, a runner who successfully breaks through the line does not get to take back an opposing player to their line, but instead simply returns alone. In another, if the runner breaks through, then he or she may choose any player on the opposing side to return and join their line. A third variation reverses the result of breaking through the line - that is, if the runner breaks through, then he or she stays on the opposing side, and if he or she fails, then the runner returns to their original side. The goal is to join the opposing wall rather than to stay in your own.