It might shock you to know that NFL football is not very popular outside of the North American continent. Instead, fans from around the world get their fix of high-adrenaline, collision-heavy sports watching rugby. Rugby plays with a football-shaped ball and there's plenty of contact, but the game is played much differently. The clock even moves in the opposite direction.
An officially sanctioned rugby match lasts 80 minutes, split into two 40-minute halves. The host team determines the length of halftime, but that length cannot exceed 15 minutes. But unlike most major American sports, the rugby clock never stops moving. Refs can add game time for injuries on the field, player substitutions, replacement of torn clothes and referee conferences. Extra time is always added to the end of the half; it is not saved for the end of the game. Overtime periods last five minutes and commence after a one-minute break. Overtime periods are played consecutively until a victor emerges.