The game started with one player who called for a number of pips, e.g. three 2's, then the next player would have to raise, i.e. four 2's or three 3's. Either the total number or the pip number had to be bigger than the previous calling as the game took turns.
If you thought your opponent was bluffing, then you could say "open!" Supposing you had two 1's and two 3's, and your opponent had one 1 and two 3's in both of your dice cups. Then your opponent called for eight 3's, and you didn't believe him and said open, then you won. If he called for seven 3's and you said open, then you lost.
Normally, 1 pip could be any number of pips; i.e. it could be 2, 3, 4, 5, or 6, so that the game could be more complicated and fun. It was like an unknown factor, because a player might only have one 2 in his dice cup, but he also had three 1's, which meant he had four 2's potentially.
