When I ask for a number, please send me a number from 1 to 20 in ESP.
The hoster will then randomly draw a number from 1 to 21.
If this number and your number added together are under or equal to 21, you win.
The amount of points you get in a round is the sum of your number plus the number the hoster has drawn, unless you bust (get over 21) then you get nothing.