Summary: This dataset contains electroencephalographic (EEG) recordings of 38 subjects playing in pair to the multi-user version of a visual P300-based Brain-Computer Interface (BCI) named Brain Invaders (Congedo et al., 2011). The interface uses the oddball paradigm on a grid of 36 symbols (1 Target, 35 Non-Target) that are flashed pseudo-randomly to elicit a P300 response, an evoked-potential appearing about 300ms after stimulation onset. EEG data were recorded using 32 active wet electrodes per subjects (total: 64 electrodes) during three randomized conditions (Solo1, Solo2, Collaboration). The experiment took place at GIPSA-lab, Grenoble, France, in 2014. A full description of the experiment is available at https://hal.archives-ouvertes.fr/hal-02173958. Python code for manipulating the data is available at https://github.com/plcrodrigues/py.BI.EEG.2014b-GIPSA. The ID of this dataset is bi2014b. Full description of the experiment and dataset: https://hal.archives-ouvertes.fr/hal-02173958 Investigators: Eng. Louis Korczowski, B. Sc. Ekaterina Ostaschenko Technical Support: Eng. Anton Andreev, Eng. Grégoire Cattan, Eng. Pedro. L. C. Rodrigues, M. Sc. Violette Gautheret Scientific Supervisor: Ph.D. Marco Congedo ID of the dataset: bi2014b