The goal is to reach 12 perfect performances of a small section. (The number 12 is arbitrary, and the one I was given by Joe Mayes; it could be any number, but I like that 12 is higher than 10, and seems to usually work for me.) These performances do not have to be consecutive; in fact, the game is set up so that you are just playing them perfectly a large majority of the time. You take this small section - one you are having particular difficulty playing - and set your metronome at a speed that you can play it comfortably, maybe even a little below that. Play the section, and if it is perfect, you count that as "One".
Now, it may be time to explain what I mean by "Perfect." This requires you to be a very good judge of yourself, and a very honest one. Take everything into consideration - timing, rhythm, pulse, pitches, left hand fingering, right hand fingering, and anything else you can think of - and if even one of those things is off, then it was not a "Perfect" performance. If you struggle to get past "one," reduce the tempo, or even the length of the section - I've done this with a single chord change.
Next, play the section again, and if you play it perfectly again, then you move on to "Two." Simple, right? BUT, if it was not perfect, you subtract one, so now instead of moving up, you in fact return to zero. You will never drop below zero. So, say you've reached number 11, and during the next performance, you use the wrong finger but played the right note. That's right, you have to go back to 10, and now you have two perfect performances to reach 12. Oh, you played again, and you used the right finger, but the wrong note? Now you're back at 9. You see how this works? Great! You are moving up and down a step ladder to reach the 12th step. If you're still unsure, think of it like a platform game. If you are playing a game and die, you return to the last placed you clicked "SAVE," instead of returning to the beginning of the game (that is a technique for another time). The only difference is, you can lose all of your saves if you keep dying.
That's it, that's your game! You reach 12, and you can probably bump up the speed pretty easily. The beauty of this game is that is covers so many developments in one little game. You develop your ability to self regulate, you take the time to really listen, you can isolate a specific passage and perfect it in every way, it ensures that you perform the section correctly with consistency, and it has a high pressure performance aspect as you get closer to your goal - the closer you are, the more pressure you place on yourself to reach that number. Keep practicing, and have fun!