Slot bonus features: the free spins round, multipliers, wilds and bonus buy

If you look at the info page of a modern slot game, most of the text describes bonus features. The reason is simple: in many games a significant share of the total return comes from bonus rounds rather than ordinary spins. Once you understand how these features work, you also understand why one game gives frequent small wins and another gives long empty stretches and a rare big hit.

This guide goes through the most common bonus features and connects them to two key figures: RTP and volatility. If these terms are new to you, start with our guide how to play slots: RTP and volatility.

The free spins round

The free spins round is the most common slot bonus game. It is usually triggered when enough scatter symbols land on one spin, often three or more. The round gives a fixed number of spins played at the same stake that triggered it, and you do not pay for them.

An important difference from free spins offered by a casino: the in-game free spins round is part of the game's maths. Its value is already included in the game's RTP. Free spins handed out as a casino bonus are a separate marketing offer, explained in our guide free spins: how they work.

The free spins round almost always has something that makes it stronger than the base game:

• a multiplier that multiplies all the round's wins;
• extra wilds or wilds that stay in place on the reels;
• symbol removal, after which the more valuable symbols appear more often;
• a retrigger, where new scatters award extra spins.

These extras are what make the winning potential of the bonus round several times greater than an ordinary spin.

Multipliers

A multiplier multiplies a win by a set factor. If a payline win is €2 and the multiplier is 3×, you get €6. There are several types of multipliers:

• a fixed multiplier that applies throughout the bonus round, for example all wins 2×;
• a progressive multiplier that grows with every win or every spin, so wins are worth more towards the end of the round;
• a random multiplier that can appear on any spin or attach to a wild symbol.

A progressive multiplier matters especially for volatility: most of the round's value builds up on the last few spins, so results are very uneven. One round pays only a couple of times the stake, another hundreds of times.

Wild symbols and their variants

A wild symbol substitutes for other symbols and helps form winning lines. It usually does not replace scatters or bonus symbols. Modern slots have several wild variants:

• an expanding wild covers the whole reel when it lands;
• a wild that stays in place remains on the reel for several spins in a row, often for the whole bonus round;
• a walking wild moves one position with every spin;
• a multiplier wild multiplies every win it takes part in.

The type of wild directly affects how large the bonus round wins can be. Wilds that stay in place build up on the reels and every next spin becomes more valuable, so the chance of a win differs greatly between the start and the end of the round.

Retriggers and extra spins

In many games the free spins round can be triggered again from within the round itself. If enough scatters land again during the round, spins are added to the counter. Some games cap retriggers, others do not.

A retrigger does not change the game's RTP, because it too is included in the game's maths. It does, however, increase the spread of round results: most rounds end with the base spins, but a small share run very long and deliver a disproportionately large part of the total return.

Bonus buy

Bonus buy lets you pay a fixed amount, usually tens to hundreds of times the base stake, and trigger the bonus round straight away without waiting for scatters. To the player it feels like a fast track to the most exciting part.

What you should know:

• The price is based on the round's expected value. The RTP of a bought bonus is often listed separately on the provider's info page and may differ slightly from the base game RTP. The house edge does not disappear.
• Volatility is very high. One bought round can cost 100 stakes and return 10 or 1,000. With a small budget a couple of buys can use up the whole session amount.
• Often forbidden during a bonus. When wagering bonus money, many casinos forbid bonus buy in their terms.
• It is not available everywhere. Whether the feature exists depends on the game and the casino.

If you use bonus buy, count it in your budget as one very large bet, not as an ordinary spin.

RTP, volatility and bonus features: how they connect

RTP tells you how much a game returns from stakes in the long run. Volatility tells you how that return is distributed: as many small wins or as rare big wins. Bonus features are the main tool a game provider uses to shape volatility.

Picture two games, both with an RTP of 96%:

• A low volatility game gives most of its return through ordinary spins. The bonus round comes often but is modest. The balance moves little and the session lasts a long time.
• A high volatility game keeps a large part of its return for the bonus round, which comes rarely but can deliver a very big win thanks to progressive multipliers and wilds that stay in place. In the base game the hit frequency is low and the balance can shrink for a long time.

In both games the expected loss is the same: on average €4 per €100 staked. What differs is the path there. In a high volatility game it is far more likely that you lose the session amount before the first bonus round, and also more likely that you land a single big win.

A game's info page usually lists the RTP, the volatility and the maximum win. A high maximum win, for example several thousand times the stake, almost always points to high volatility. You can check what RTP means for your own stakes with the RTP calculator.

Practical tips

• Choose volatility to fit your budget. With a small budget in a high volatility game, there is a high chance you never see the bonus round.
• Do not chase the bonus round. Every spin is independent. A long gap since the last bonus does not make the next one more likely; that is the gambler's fallacy.
• Read the game's info page. It states what triggers the round, which extras it has and whether the RTP depends on the chosen mode.
• Choose a licensed casino. Casinos with an Estonian licence are under state supervision. You can find a selection on the slot casinos page, and for Megaways games on Megaways casinos.

Slots in Estonia are allowed from the age of 21. Bonus features are built to create excitement, and "almost a bonus" moments can tempt you to play longer than planned. Set yourself a time limit and a loss limit, and if gambling starts to worry you, you can find help at peaasi.ee.