This is a great putting game that will not only help you with your putting but also can make your practice more interesting and enjoyable. You can play this game by yourself, or better yet, find some people on the putting green to play against.
Pull back is simpler and places more of an emphasis on short putts as opposed to longer putts. The game is easy to score, every hole is a par two. I suggest picking putts of varying lengths, perhaps having the player with the honor choose the next putt. Every putt that does not go in the hole must be drawn back 3 feet, or approximately one putter length. This means that even a putt hanging on the lip of the hole represents a 3 footer coming back. Each hole is played until the ball is holed out.
Safety pull back assigns a benefit to good lag putting, but will also test your ability from short range. The game is played the same way, but with on exception. With every putt, there exists a safety zone where the ball is safe and does not need to be drawn back away from the hole. This safety zone is marked by the hole itself, with a 3 foot wide, 180° semicircle around the back side of the hole. The concept here is that if you hit a good approach putt, as defined by a putt that reaches the hole and stays within 3 feet, then you are rewarded and can play the ball where it lies. Any putt that comes up short, even by an inch, rolls too far, or otherwise misses this safety zone, will need to be pulled back 3 feet, or approximately one putter length. Each hole is played until the ball is holed out. Bear in mind that the safety zone resets with each putt and exists for second and subsequent putts as well.