Solitaire Zero21 Fun numbers game with solitaire flavor to relax and unwind while keeping your mind sharp. Collect all the number cards on the board and progress through 75 unique levels. The goal of the game is to collect all number cards from the board. Your sum must stay between 0 and 21. In order to do that you can also use special cards such as MIN, MID or MAX. These cards set value of your sum to corresponding value.