In order to study the concurrent activity in subjects interacting in cooperation or competition activities, the issue of the simultaneous recording of their brain activity became mandatory. The simultaneous recording of neuroelectric activity of the brain is called "EEG hyperscanning". We would like present results obtained by EEG hyperscannings performed on a group of subjects engaged in a card game. The EEG hyperscannings have been performed with the simultaneous use of high resolution EEG devices on groups of four subjects while they were playing a card game. We estimated the concurrent activity in multiple brains of the group and we depicted the causal connections between regions of different brains. Results obtained in a study of several groups recorded by the EEG hyperscanning reveal larger activity in prefrontal and anterior cingulated cortex in different frequency bands for the player that start the game when compared to other players. EEG hyperscannings will open a different area for the study of neuroscience, in which the activity of multiple brains during social cooperation could be investigated.