Soccer
In Britain, people call soccer "football," and football is referred to as American football. Although it's not exclusively a game for children, soccer is one of the most popular games for British children to play. The majority of kids who play soccer are boys, but girls also sometimes join in. It's often played at recess in school, as well as in gym class and in local soccer teams outside of school.
Conkers
Conkers is a traditional British game. Children collect "conkers," which are nuts that come from the horse chestnut tree. With the help of an adult, kids make a hole through the middle of the conker using a metal skewer. A 10-inch string is then threaded through the hole and tied at the end to keep the conker in place. In pairs, children battle their conkers by hitting them into each other until one is destroyed.
British Bulldog
British Bulldog is a game best played with five or more kids. All except one line up on one side of a playground or pitch. The other child is the Bulldog. The Bulldog stands in front of the lined-up kids. These kids have to run to the other side of the playground without getting caught by the Bulldog. The Bulldog has to catch someone long enough to say "British Bulldog, one, two, three." If they do, that person also becomes a Bulldog.
Stuck in the Mud
Stuck in the Mud is a game that requires at least three players, though more are better. One player is "it." This child has to chase the other players and tag them. When players get tagged, they become "stuck" and have to stand with their arms out. A player who isn't stuck can free a player by touching them on the hand. The game was first documented in Britain in the book "London Street Games" in 1916.