Line up!

5 or 15 lines? 25 or 243? The number of paylines does normally not affect the RTP of the game. And if it does, game designers have usually worked hard to make the difference as small as possible. So why do we keep changing it?

Mathematical volatility is one of the key factors affecting the feel of the game. Although there are a number other aspects of the number of paylines, this post focuses on its direct relation to the volatility. We need to set the number of paylines before designing the actual payout structure, or it will be difficult or impossible to give the game the desired momentum.

As we increase the number of paylines, we lower the volatility of the game. A high volatility means that wins tend to get bigger but occur less often. Conversely, a low volatility usually means that we win often but big wins are very rare or non-existent.

Also, even though increasing the number of paylines makes us win more often, it might happen that we increase the risk of winning less than we pay for each spin.

Playing the game with a different number of paylines can give the game an entirely different feel. Most players tend to play the maximum number of available paylines. Therefore game designers typically optimize the payout structure based on the maximum number of lines.

Modeling a game with Slot Designer, we can plot the following charts showing balance (Credit Meter) vs game rounds for typical playing sessions. We start with 3000 credits and play 1000 game rounds with a total of 27 credits per spin, but with different numbers of paylines.

In the first chart, we play 9 lines, 3 credits per line, making this a medium volatility game (σ=2.08).

9 lines/3 credits per line

This graph indicates some reasonable chances at peaks but at the same time the losing streaks aren’t so long.

In the next chart, we see a typical playing session of the exact same game, but on each spin we play 27 credits on only one payline.

1 line/27 credits

As is to be expected in this high volatility game (σ=6.33), the wins are fewer but bigger. In this particular case, we got lucky and hit a big win early during the session, but the losing streak that follows is long. Some players might enjoy the thrill of this game, while others feel they don’t win sufficiently often.

The last chart shows the same game played with one credit on 27 lines, making it a low volatility game (σ=1.15).

27 lines/1 credit per line

This graph is comparatively smooth with only small jumps. Unless there is a big jackpot to play for, this game would feel rather boring to some players, while others might find it entertaining due to the frequent wins.

While being but one of several interrelated factors, different volatilities appeal to different types of players, hence the number of paylines plays an important role in making the game an enjoyable experience!