We can add a second pay rule to the game in Figure 1, which wins 100 credits when we get A on the left 2 reels, but not on the 3rd reel. We can also see that as the chance of winning increases the prize won must correspondingly decrease to achieve the same RTP. Indeed, their volatility is so extreme that neither would be a practical design. The game that wins every time has a very low volatility, and the other a very high volatility. The key difference between these two games lies in their volatility. These two games have the same RTP, yet would be fundamentally different to play. In the previous section we also calculated a RTP of 100% for a game that wins 1000 credits once in every 1000 games, and zero every other play.
If we have a game that wins 1 credit for every play, the average win is then 1 credit, and with an average bet of 1 credit this gives us an RTP of 100% (Equation 3).
