Bonus features are where much of the creative, interactive fun of slot machines is focused.

Much of game development centers on getting the bonuses just right to get us to try a game and keep us playing once we’re there. As one slot exec told me in 2013, “Bonuses are what it’s all about.” What form the bonuses take is limited only by designer imagination and public acceptance. Some casino bonuses resonate so well with the public that gamemakers turn to them over and over again, adding new twists and wrinkles as they go. Among the most popular formats are:

  • Wheel spinning bonuses
  • Pick’em bonuses
  • Free spins bonuses
  • Mystery bonuses
  • Community style bonuses
  • Bonus slots
  • Free bonus slots

In this chapter, we’ll look at how each format works, with examples of some popular favorites



In their classic form, wheel bonuses involve a mechanical wheel fixed at the top of a slot machine. The wheel is divided into wedges containing prize amounts. When you win a will spin, you touch a button or touch the screen to start the spin. When the spin stops, you win the indicated prize amount. The concept has expanded, so today there are wheels on video screens, and wheels used to select a bonus event as well as to award credits.

Wheels are driven by random number generators, just like slot reels. The segments don’t have to occur in equal proportions.

10 segment wheel

If the wheel landed on segments equally as often, we could tell a few of things by looking at the machine:

  • We would get the top bonus of 1,000 credits an average of once per 10 spins of the wheel.
  • We would get the bottom bonus of 20 credits an average of once per 10 spins of the wheel.
  • The average return per spin would be 213 credits.

Bonus wheels don’t actually pay their top prizes so often. Game designers need events that occur frequently enough to hold player interest, while offering the chance at a big payoff. To achieve that balance, game designers use something much like the virtual reel described in Chapter 3. Wheel segments can be of equal size, but not have equal chances of stopping at the indicator.

To create a hypothetical example, a 10-space wheel could be set up with 50 random numbers:

Wheel spins

With that number set, we can tell the following things:

  • The top prize of 1,000 credits now occurs only once per 50 spins.
  • The bottom prize of 20 credits still comes up once per 10 spins.
  • The set is weighted so that 60- and 50-credit wins are the most frequent.
  • The average win is 105 credits.

With an average win less than half the 213 you’d get if all numbers occurred equally as often, game designers can have the bonus events occur more often. And since the weighting of numbers means frequent 60- and 50-credit wins, players aren’t discouraged by the bottom 20-credit wins coming up too often.

The same kind of weighting applies to bonus wheels that initiate other bonus events in addition to awarding credits.

Not all bonuses occur equally as often in Bally’s Michael Jackson: King of Pop, WMS’ Journey to Oz or any other game that uses a wheel spin to initiate free spin or pick’em bonuses. The most lucrative bonuses will occur the least often. One more twist on the bonus wheel has been Bally’s U-Spin technology. Introduced on the game Vegas Hits, U-Spin puts a bonus wheel atop the machine, but also puts a video representation on the screen.

You touch the onscreen wheel and move your finger to drag it forward or backward, fast or slow. When you let go, it moves at a speed that corresponds to your motion. The wheel at the top of the game moves at the same speed as the wheel on screen, and in the end they stop on the same space. It’s a cool visual effect that gives players the illusion of control, but the result is determined by a random number generator.

Key Takeaways
  • Wheel spins are used to award bonus credits or launch other bonus events.
  • Results are determined by a random number generator.
  • A virtual reel concept can be used so top prizes occur less often than smaller awards.
Table 1-random numbers


Pick-a-prize bonuses, or just pick’em bonuses, have been a staple of video slots since the late 1990s. They can be as simple as touching one icon on the screen to collect bonus credits. They also can be longer events where you keep picking until you touch an icon that ends the event.

Here are some things you should know about pick’em bonuses:

  • Pick’em bonuses are designed to make you an active participant in the game.
  • Possibilities are set by a random number generator.
  • You touch and icon on the screen, which then is either overlaid or replaced by a prize amount.
  • Your choices matter, though there is no strategy that can find the biggest reward.
  • Some games use pick’em bonuses to award icons, free spins or launch other bonus events.

One classic one-pick game is Reel ’Em In, in which the player picks one fisherman to reel in a fish. The bigger the fish, the bigger the bonus. A long-lasting multipick favorite is Jackpot Party, where the player picks from a grid of gift boxes. You keep picking until the prize you pick reveals a party pooper instead of a prize. The pooper ends the bonus.



Players often ask if their choices matter, or if the bonus award is predetermined.
Do you win the prizes you pick, or are the prizes adjusted so you whatever you pick, you get what you were supposed to?
The answer is that you really do get what you pick, and your choices matter.
Let’s make up a round where you’re picking color segments from a 16-space grid, like so:

Color segment table

When you touch the screen, either you will get bonus credits, or a “Round Over” message.
You can’t see what color blocks hide which awards, but those have already been set by the RNG.

It’s as if there is a second grid under the first. If you could see it, it might look like this:

Color segment table - 2

If you pick the second block in the second column, you will get the top prize of 100 credits and keep picking.

If you pick all the credit amounts without hitting “round over,” you get all 395 credits.

If your first pick is “round over,” your bonus is zero.

There is no preset bonus award that you are “supposed” to win. The RNG doesn’t set a prize for you of, for example, 75 credits, then adjust what’s in the blocks you pick to get that 75 total. The RNG just set the possibilities, and you get whatever your picks bring. There is no strategy to find the high-paying blocks. Because you choices make a difference, you get the feeling of control. But since there’s no way to tell what’s in each block, no strategy will yield results any better than random picking.



Players sometimes struggle with the idea that bonus payouts can vary with your choices.
“How can it not be a fixed amount?” they ask. “Doesn’t there need to be a fixed amount so they can program the payback percentages?” As we’ve seen in earlier chapters, games aren’t programmed to always hit a fixed payback percentage. Instead, the odds of the game are set so that over hundreds of thousands of plays, they will lead toward a targeted percentage.
That’s the way it works with awards on pick’em bonuses. Programmers don’t need to know the amount of every award. They just need to know an average award, given random choices.

For an easy example, let’s make up an easy, one-pick bonus event. Let’s say we have an African wildlife-themed slot game, with a one-pick bonus in which you choose either a lion, and elephant or a hippopotamus.
The RNG will randomly scatter awards so that picking one brings 25 credits, another brings 50 and the other brings 75.
There is no way to know which is which. What you see on the screen is this:

Credit awards are hidden from view, just as on the color block game. For example, they might be distributed like this:

The order in which the awards appear changes with every play. Your pick makes the difference of what you get on any one free bonus round. However, the game designer knows that over many plays, about a third of picks will bring 25 credits, a third will bring 50 and a third will bring 75. The average award will be 50 credits, and the designer can use that in building the odds leading to a targeted payback percentage.



Over the years, pick’em bonuses have been used in many ways to give you an active part in playing the games.
Here are a few examples:

Fortune cookie-pick a dish

The bonus event gave you a Chinese restaurant menu on screen and had you pick dishes in different categories – a poultry dish, a seafood dish, and so on. Each dish you picked was worth bonus credits, and after you’d made your picks, you could see if you picked the best dish in the category.

Flinstone-Bedrock bowling


The Bedrock Bowling bonus started with you choosing a stylized bowling ball. Did you want the ball made of cash?
The Stone Age stone ball? Then you could let it fly down the lane to see if you could strike it rich.

Deal or no deal


Tying in with the TV show, Deal or No Deal slots offered the Suitcase bonus slots, in which you’d try to have your picks eliminate the suitcases with the least cash.

Pick'em Battle Ship


The bonus event played much like the classic board game. You’d touch squares on an ocean grid, trying to locate ships to sink them for cash. That’s just a sampling of what can be done with pick’em event. There have been hundreds of these, and there will be hundreds more with plenty of new twists and fresh fun to come.

Key Takeaways
  • Pick’em bonuses are designed to get players to interact with the games.
  • Your choices really make a difference in the size of your bonus.
  • Game designers can used an expected average award to help lead to a targeted payback percentage.
Pick'em Bonus Round-1


Free-spin bonuses have become the most widely used bonus events on modern slot machines, and they’re just as advertised. You get a number of free spins of the reels, during which you collect payoffs on any winners without having to make any wagers.

A few important points about free-spin bonuses:

  • Free spin bonuses are designed to add volatility to slot games.
  • Many free spin bonuses use the same reels as the regular games.
  • Some free spin bonuses add extras, such as wild symbols or stacked symbols not available on the main game.
  • When free spins are on the main game reels, you can get extra free spins if the trigger symbols come up again.



When video slots first achieved U.S. popularity in the 1990s, the most popular slot bonus events were pick’em games.There was room for variation.

The Australian slotmaker Aristocrat Technologies was focused on free spins even while American manufacturers WMS Gaming and International Game Technologies put pick’ems first.

The big change came in the middle of the first decade of the 21st century as one-cent slots displaced five-cent slots as player favorites. Five-cent, or nickel, slots were designed to be low-volatility games offering players high hit frequencies and extended play.



Penny slots needed to put more volatility in the games in order to offer players paybacks worth playing for. On nickel games, fewer credits can be a worthwhile prize. Take the Jackpot Party field of gift boxes. If a player makes a few good picks and accumulates 200 credits, that’s worth $10 on a nickel game.

At many casinos, a player who won $10 in the 1990s could have bought a lunch buffet and had a substantial meal. What if you put the same game on a penny format? Then a 200-credit win is worth only $2. That won’t come close to buying a lunch buffet – it might fetch a bag of chips and a candy bar at the snack bar. Free spin bonuses are a way to give the player a chance at bigger prizes. All the payoffs available on the main game are available, right up to the top jackpot.



  • Free spins give players a chance to accumulate thousands of credits.
  • If you win additional free spins while in the bonus, you can have long stretches without making a bet.
  • It’s possible to have free spins with no payoff.

The average free-spin bonus is about the same as the average pick’em bonus, but the distribution is far different. There are both more very large bonuses and more very small bonuses when free spins are used.


The first free spin games added no extras. The spins stood on their own as a bonus event.
That’s a format still used today, although some games add more bells and whistles.
Take the Aristocrat game Queen of the Nile, a longtime player favorite.

  • 15 free spins are triggered when you land three pyramid symbols on the screen.
  • The pyramids herald the bonus by shining beacons out their peaks, to the tops of their spaces.
  • During bonus spins, winning combinations pay the same amount as in regular play.
  • If you land another three pyramids on the screen during free spins, you win 15 more spins.


That’s a format that has stood the test of time.
Many free-spin games work in much the same way.



Many free spin games go beyond the classic free-spin bonus to give players an enhanced experience in the slot bonus event.

Here are a few examples of ways free spins have been used:

Extra spins


In the “Smooth Criminal” bonus, Jackson’s music video is overlaid on the reels during free spins. At the sound of cymbal clash, Jackson stops, points, and the indicated symbol turns wild.


Wild symbols add to your potential wins. In Wonder Woman Gold, there are extra wild symbols on the reels. In Wonder Woman Wild, wild symbols randomly are added to the screen to substitute for the low-paying A, K, Q and J symbols.


All the emphasis is on big payers in the free spins bonus. All the low-paying symbols are eliminated, and what are left are long stacks of the high-payers – Bengal tigers, black tigers, huntresses and wild symbols. A screen full of the same symbol stacks brings roaring big wins.


You’re part of the action in a game that has a camera to capture your image. The Celebrity Spin Cycle Bonus launches when the police pull over a speeding car driven by you. You’re a reel symbol, too.


Free spins feature Sticky Stacks. Full columns of stacked symbols stick in place for the next spin, opening big win possibilities.


WMS, and now its parent company, Scientific Games, offer a number of games with respins. Zeus is one of them. If the first column is filled with a Zeus symbol, all Zeus and wild symbols are held in place during two respins. You can also win standard free spins with three lightning bolts on the reels.


Players can choose their volatility in the free spins bonus by choosing either fewer free spins with a big multiplier for winnings, or fewer spins with a small multiplier.
For example, you could pick five free spins with winnings multiplied by 10, 10 spins multiplied by five, 15 by three or 20 times 2.
Pick five free spins, and you’ll win less often but have bigger payouts when the winning spins come. Pick 20 spins and you’ll win more often, but individual wins will be smaller, giving you a less volatile game.


A different take on choose your volatility, Goldify lets players choose a symbol. Payoffs then are doubled on winners using that symbol. Doubling high-paying symbols leads to higher volatility, while doubling more frequent winners lowers volatility. You won’t find all these specific games in any one casino. Games come and games go, but bonusing tools remain available to game Extra wilds, high-paying stacks, respins and choose your volatility features all are tools in use in many games today.

Key Takeaways
  • Free spins are widely used to bring big wins to low-denomination slot.
  • Big wins on free spins are offset by the possibility of zero-payback bonuses.
  • Extra wild and stacked symbols, respins and choose your volatility features all are used to make free spins attractive to players.



With all the variations available on live slots and online slots, especially since the advent of video slots, two things are almost absolutes:

  • Your reels or screen show you exactly why a payback is coming.
  • Game results are pure chance.

Whether you’re seeing winning symbols on a payline, a credit segment on a bonus wheel or a prize determined by your choice in a pick’em bonus, you see why the payoff is made and what it is worth.

There is nothing you can do to change where the reels stop, which wheel wedge wins or which prize a pick’em icon is hiding. That’s all left to chance.

What makes those two statements “almost absolutes” instead of “absolutes” are the availability of mystery bonuses and skill-based bonuses.



Instead of being triggered by symbols landing on the reels, mystery bonuses are awarded randomly as a complete surprise to the player.

Mystery bonuses were devised by John Acres, who today is CEO of Acres 4.0. In more than 30 years in gaming Acres invented electronic player tracking systems as well as progressive jackpot systems.

The first mystery bonus game to make a big splash in live casinos was Money Time from Mikohn Gaming, in 1997.

Bonus Time


At random times, flashing lights and sound effects would signal the arrival of “Money Time.”

During the Money Time period, all active players at the bank of machines would receive random awards until a full, randomly selected amount had been paid. Today, mystery triggers are used most often on games with multi-tiered progressive jackpots, but some non-progressive bonuses are mysteries, too.

Take WMS Gaming’s Super Jackpot Party, where you can get to the gift-box pick’em bonus in two ways.

  • If noisemaker symbols land on the first, third and fifth video reels, you hear the cheer “Jackpot Party!” and the bonus begins.
  • At random times, the chant is “Surprise Party!” and that brings the same bonus event.
Mystery Fish

At Surprise Party time, there’s no landing noisemakers on the first and third reels, then hoping the fifth reel brings the bonus. There’s no clue the party is coming at all, until it’s here.

Similarly, in WMS’ Goldfish, one bonus is triggered on the reels. Three fish food canisters launch a pick’em bonus.

Other bonuses are mysteries, themed on the different fish in the game. Fanfare sounds, drums roll, and one of the five fish drop from a seascape in the top box into a fish bowl on the main screen to kick off a bonus event.

There is no hint on the reels that a bonus is about to happen. It gets you by surprise.

Mystery bonuses are triggered by a random number generator, and can be programmed in several ways:

  • They could launch at a randomly selected time.
  • They could launch after a randomly selected number of coins have been played.
  • They could launch when a jackpot or prize pool reaches a randomly selected amount.

You can find more detail on how that random selection works in Chapter 6: Video Slot Progressives, since progressives have the largest segment of mystery games.



Here’s a segment you’re likely to see growing in the coming years as casinos reach out to players used to games of skill online.

In 2015, Nevada legalized fully skill-based gambling. Once the Nevada Gaming Commission approves regulations, we’ll start to see what gamemakers can do with the format.

For now, there already are games in the field with elements of skill in bonus events. The older regulation in Nevada permitted up to 4 percent of a game’s payback to be based on skill, and such games are available in many states.

That’s not enough to make skill games a profit opportunity for players. That 4 percent might mean a game might offer a payback range from 88 to 92 percent, depending on skill, but it’s still a money-earner for the house.

Here are some of the games with skill-based bonuses that have made it to casino floors.

Skilled Base

PONG, Bally Technologies:

Bally was a pioneer in skill-based bonuses in 2007 with Pong, based on the 1970s arcade game that was essentially a two-dimensional table tennis simulation. The slot machine bonus was a game of Pong, and if you could beat the machine, you got a bigger bonus.

BREAKOUT, Bally Technologies:

Breakout was a follow-up to Pong in the ‘70s in arcades, and in 2008 on the slots. You deflect a ball toward a block of colored blocks. Each block you hit disappears and adds to your bonus, but if it bounces back past you, the round is over.

TULLY’S TREASURE HUNT, International Game Technology:

In the bonus, you use a joystick to guide a sea turtle through an underwater chase to collect bonuses. Make him swim through the right icons, and your bonus grows.

CENTIPEDE, International Game Technology:

Based on an arcade classic, Centipede rewards skill as you use a joystick to move into position, then one of four buttons to fire at the crawling centipede. Destroy the full centipede, and you move to a more difficult second level for more bonuses.


GTECH has since merged with IGT, but under a license with online game provider PopCap Games, it introduced Zuma in 2013. A skill-based bonus event has the player take the role of the Zuma frog as it shoots colored balls to hit the moving Kahtiki Khan boss.

Players who don’t trust their skill, or would rather just have random rewards, have the option of playing free spin bonuses on Tully, Centipede or Zuma, or letting the game computer play for them on Pong or Breakout.

All of these games have carved out small followings, though none have been megahits.

Bally temporarily put skill-based games on the shelf after breakout, but in 2016 plans to introduce Space Invaders, another game with a bonus based on an arcade favorite. Gamemakers believe younger generations will demand games of skill, and are preparing to meet the demand.



Even players who don’t trust their skill like to feel as if they have some control over outcomes. Gamemakers sometimes address that with “perceived skill” or “illusion of skill games.”

Perceived skill games can introduce real skill in bonus events, but award bonuses randomly.

One example is SkeeBall from Bally. The bonus event is based on the arcade favorite SkeeBall, in which you roll balls up a lane, trying to land them inside concentric circles. The smallest circles are worth the most points.

In SkeeBall the slot:

  • A SkeeBall game appears on the screen.
  • You touch and drag balls on the screen, and when you let go you can roll them fast or slow.
  • You can try to roll the balls straight, or you can try to bank them off the sides toward the circles.
  • If you land the balls in the circles you get points.
  • There is real skill in all that. A good player will earn more points than a poor one.


When the round is over, your points are exchanged for a corresponding number of tickets, and you take the tickets to an onscreen redemption shop.

In the shop, there are shelves of gifts, each with a ticket price. You choose: Do you want to redeem a lot of tickets for the giant stuffed animal, or divide your tickets to get several smaller prizes?

After each selection, a credit award is revealed under the chosen prize.

That’s where the randomness factors in. The awards you receive are determined by the RNG, and not by how many points you’ve earned. Skilled players will earn more tickets than unskilled tickets, but their credit awards will be about the same.

Bally has used the perceived skill format on a number of games. IGT used it on Big Buck Hunter, which attacked a plastic rifle to the side of the machine for use in a hunting bonus. Better shooters got more points, but not necessarily bigger rewards.

Perceived skill games are likely to have a place in casinos for a long time, but casino operators and game manufacturers alike are banking on the big growth coming in true skill games.

Key Takeaways
  • It’s not necessary to land bonus symbols on the reels to trigger mystery bonuses.
  • Mystery bonuses can be triggered by randomly selected times, amounts of play or jackpot size.
  • On games with skill-based bonuses, skilled players will do better than unskilled players, but do not have an edge on the house.
  • Perceived skill games involve real skill in game play, but credit awards are random, so unskilled players will get about the same paybacks as the skilled.



Slot machines are solitary experiences, man or woman vs. the machine, without the win-together feel that comes when a whole blackjack table wins on a dealer bust, or a hot shooter has a whole craps table cheering and giving high fives.

Gamemakers have tried to give players in live casinos a heightened social experience with community-style slots in which multiple players are involved in a free bonus event at the same time.

Community bonuses can come in several forms:

  • Simultaneous bonuses in which players may or may not participate in the same event.
  • Bonuses where all players win together.
  • Bonuses in which players take turns building credits for each other.
  • Bonuses where players compete against each other.



The first community slots bonus game on a live slot was Bonus Road Rally, by A.C. Coin. In Bonus Road Rally, a display above a bank of $1 IGT three-reel mechanical slots had a track and 10 cars, one for each machine at the bank.

As customers played the main slot game, their wagers would advance the cars along the track.

The player whose car reached the finish line first won the biggest bonus.
Bonus Road Rally was a game ahead of its time. It never really caught on with players. Instead, the breakthrough for community games would come about a decade later, once video slots were well established.

Community Beginnings



Simultaneous Slot


In 2005, International Game Technology brought its popular Wheel of Fortune theme to community-style live slots with Wheel of Fortune Super Spin.

Super Spin features included:

  • Nine seats and game screens circling a colossal wheel.
  • Each customer played his own base game.
  • When a player won a bonus wheel spin, he could play now or wait to play the bonus later.
  • More than one player could choose to play their bonuses on the same wheel spin.
  • Each player had his own wheel wedge indicator, and the wedge that stopped in front of him determined his bonus.

With that format, customers could play together, but their slot bonuses would be different sizes. You weren’t necessarily cheering for your neighbor, because you wanted the highest-paying wedge. A.C. Coin used a similar format in Super Bankroll Bonus, which had a central column that contained stylized depictions of U.S. currency.

In the bonus event, the column whirled around and around, and where it stopped determined your slot bonus size. If two or more players were in on the bonus, they’d get different payoffs, because the currency that stopped in front of you was different than that in front of your neighbor.



The pace-setter in win-together community-style bonuses has been WMS Gaming. It launched its Community Gaming lineup with Monopoly Big Event, introduced to the industry in 2005 and rolling into casinos in 2006.

Monopoly Big Event features include:

  • Individual games with their own free bonus events
  • A large plasma screen stretching over the tops of several machines.
  • Among the bonus events is an around-the-board bonus, where virtual dice rolls take players around a Monopoly board on the plasma screen.
  • Players win credits for each Monopoly property on which they land.
  • Players who bet more or play faster earn a multiplier for bonus credits won.
Win together


This is a win-together experience because players all collect the same properties at the same time. If the dice take players to Marvin Gardens, all players win the Marvin Gardens credit award. However, players won’t win exactly the same amount. Since wager size plus speed of play earns a multiplier, you might find a win of 2,000 credits multiplied by two, while your bigger-betting neighbor has it multiplied by three.

That format had success for WMS, and it turned to win-together bonuses on games including Jackpot Party Community and Press Your Luck.


Collaborative Bonuses


Collaborative bonuses are a spinoff of win-together games in that players all collect the same bonuses at the same time. However, collaborative bonuses have the added feature of players taking turns in parts of the game that build bonuses.

A win-together game might have a single player push a button or touch a screen to launch an event that then is played out by the random number generator, or might have a single player taking action for the entire group. Collaborative bonuses have multiple decision points, and all players take part. WMS again turned to Monopoly to introduce the concept with Monopoly Bigger Event, Monopoly Bigger Event features individual games with their own bonuses, plus a number of collaborative bonuses on big screen overhead.

Among the collaborative bonuses are:

  • Water Works and Electric Company. Players take turns choosing water valves or power switches for bonuses.
  • Community Chest and Chance: Players take turns drawing cards for bonuses, including chances to launch other events.
  • Around the Board: Players take turns launching onscreen dice for a trip around the Monopoly game board.

If you throw the big-money power switch, or launch the dice-roll that takes the group to Boardwalk, you’re a hero to all. If you land on a smaller bonus, others still have a chance at the big one.
International Game Technology also has players working together in Hot Roll Community, part of its Connected series of games.

In the Hot Roll Community bonus:

  • Three players go to the bonus event together.
  • They take turns rolling virtual dice by touching and dragging on individual screens, then flinging toward the big screen overhead.
  • When one player has a winning roll, all players collect bonuses.
  • A roll of 7 ends one player’s participation for the round, but the others keep rolling until all three seven out.
  • Players who have sevened out keep collecting bonuses as long as at least one other shooter is active.

It’s a win-together experience, but it’s also collaborative since your rolls build bonuses for other players.



The archetype of competitive bonuses is Reel ’Em In: Compete to Win by WMS.
Players go to fishing bonuses at the same time on the overhead screen, but they don’t win the same prizes.

In the Fishing Derby bonus:

  • Each player has a fishing line in the virtual sea on the plasma screen overhead.
  • Fish of different sizes swim past.
  • You earn bonus credits for each fish you catch, with bigger bonuses on bigger fish.
  • At the end of the round, all bonus credits are tallied, and whoever has the most wins the derby and an extra prize.

Landing the most fish doesn’t necessarily win the derby. If you land 10 small fish, each worth 25 points or less, and your neighbor lands only one fish, but it’s a 500-credit monster, your neighbor wins.

Instead of winning together, the fun here comes from competition.

As with all slot games, community-style games rise and recede in popularity quickly, and you may not find these specific games in any one casino. However, through the trend-setting games, you can spot the kinds of things game designers have in their toolkits for future community-style bonuses.

Key Takeaways
  • It’s not necessary to land bonus symbols on the reels to trigger mystery bonuses.
  • Mystery bonuses can be triggered by randomly selected times, amounts of play or jackpot size.
  • On games with skill-based bonuses, skilled players will do better than unskilled players, but do not have an edge on the house.
  • Perceived skill games involve real skill in game play, but credit awards are random, so unskilled players will get about the same paybacks as the skilled.



  1. What kinds of prizes can you win on bonus wheels?
  2. When wedges on a bonus wheel are of equal size, are all results equally likely?
  3. What is a pick’em bonus?
  4. True or false: The random number generator determines your prize in a pick’em bonus, and your picks are just for show.
  5. Free spin bonuses: A. Makes extra-large wins possible even for penny players; B. Enable you to play for long periods without betting, especially if the free spins can be retriggered during the bonus; C. Add volatility because large wins are offset by rounds of small or zero wins; D. All of the above. E. None of the above.
  6. Name some extras gamemakers use to add interest to free spins beyond the game on the main reels.
  7. What causes mystery bonuses to launch?
  8. What’s the difference between a skill-based bonus and a perceived-skill bonus?
  9. True or false: Community-style slot machines were invented after video slots rose to popularity.
  10. On win-together games, do players always win the same amount of credits?


  1. On bonus wheels, you can win credits, multipliers or launch other bonus events, though not all games have all those possibilities.
  2. A wheel divided into equal-sized wedges does not necessarily give each wedge an equal chance of being the winner. A random number generator determines the winner, and some wedges can be assigned more random numbers than others.
  3. A pick’em bonus is an interactive event in which you touch icons on the video screen to reveal bonus awards.
  4. False. Your choices in a pick’em bonus are not just for show. A random number generator sets the possibilities, but your picks determine your prize.
  5. D. All of the above. Free spin bonuses make extra-large wins possible even for penny players; enable you to play for long periods without betting, especially if the free spins can be retriggered during the bonus; and add volatility because large wins are offset by rounds of small or zero wins.
  6. Among the tools gamemakers use to add interest to free spins are extra wild symbols, extra stacked symbols, respins and choose your volatility formats.
  7. Mystery bonuses are launched by a random number generator, and it can be according to randomly selected times, amount of play or size of prize to be awarded.
  8. On skill-based bonuses, player skill directly affects how much you win. Perceived-skill bonuses may involve skill in accumulating points, but translating those points into your credit prize is done by a random number generator.
  9. False. The first community-style bonus, Bonus Road Rally, was on three-reel mechanical slots and came in 1996, shortly before the breakthrough of video slots.
  10. On win-together games, players do not always win the same amount of credits because a multiplier can be added so that those who bet more or play faster get more credits

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For nearly 25 years, John Grochowski has been one of the most prolific gaming writers in the United States. He’s been ranked ninth by GamblingSites among the top 11 gambling experts at Gambling Sites and his Video Poker Answer Book was ranked eighth among the best gambling books of all time.