Our Concentration game was a rhythm elimination game - great for b-day parties. Everyone sat in a circle, slap knees, clap hands, snap left hand, snap right hand while saying "con-cen-tra-tion, keep in rhy-thm, cat-e-gor-y, names of _____________" (boys, girls, foods, cars, etc.) Whoever broke rhythm or repeated was out, until one was left, who was the winner.