This logical card game is just made for the geek in us. Utilizing cards with variables (A, B, C & D) and familiar logical operators such as 'Not', 'And', 'Or', 'If-Then' and the dreaded 'Parenthesis' (and some gotcha cards such as 'Fallacy!'), players take turns creating and changing up to four lines of 'true' statements. Each player tries to prove that they (their variable) exists (is definitely true) and everyone else...doesn't. Finally, with the Ergo card, whoever at last exists gets the points. A fun romp and definitely one for the gray matter in us all.