Double Only Cricket

Double Only Cricket is played the same way as Cricket, except that a double of each designated cricket number must be hit before a player can go further with that number. Once double is hit, that number is allowed to open. Then that double, and all other doubles, triples, and singles of that number count. For example, to start the 20's each player must hit double 20. After getting double 20 then a single 20 would close the number. A double would close and score 20 points, and a triple would close and score 40 points. So, it is impossible to close a number with one dart.

Options:

Hit & 'open' the numbers 15-20 and bull’s-eye in any order. Hit & 'open' the number 20 first, then in order 'open' numbers 19, 18, 17, 16, 15 & bull’s-eye. Hit & 'open' the bull’s-eye first, then in order 'open' numbers 15, 16, 17,18, 19 & 20.