As Michiel Sovijärvi-Spapé, one of the researchers explained "It's well known that people who communicate face-to-face will start to imitate each other. People adopt each other's poses and gestures, much like infectious yawning. What is less known is that the very physiology of interacting people shows a type of mimicry - which we call synchrony or linkage."
The game that people were playing in a study is called
Hedgewars, where they had to manage a team of hedgehogs and equip them with guns and artillery to shoot the opposing team. They players were assembled into a team to play against the computer. They were also playing against each other. As the game became more competitive, the more in sync were the player's emotional responses. Above you can see the screenshot from the Hedgewars game.