What makes a slot machine stand out?

By Ric Anderson

Monday, Dec. 21, 2015 | 2 a.m.

Slip in a $20 bill, hit the button and see what happens. You’ve played one slot machine, you’ve pretty much played them all, right?

Wrong. People who frequently play slots have favorites, based on factors that go beyond how often the game pays off.

What sets apart one slot machine from another?

Consider the Buffalo series of games — the original, Buffalo Deluxe, Buffalo Grand and Buffalo Stampede. Enter any casino and you’ll find them. Buffalo has been named the top-performing game for four consecutive years in the annual Goldman Sachs Slot Survey.

“It’s insane how popular it is,” said Paul Riley, a London-based blogger for Gamingslots. “It seems to be everywhere now. At one time, you might see one here or there; now, it’s like casinos have their own Buffalo areas.”

What makes the game such a hit might surprise you. It’s largely about math.

Slot games are designed around mathematical formulas that determine the frequency and size of payouts. High-volatility games are built on formulas that generate massive but rare payoffs. Low-volatility games yield smaller payoffs more regularly.

Players say Buffalo strikes an almost perfect balance between the two. The game appeals to a broad range of players, from those who seek fat payoffs to those who are content simply to receive lots of spins. Buffalo’s formula tends to keep players at the game for lengthy periods, thanks to a bonus design that provides free spins.

“The success of the whole game is really based on Aristocrat’s mathematics,” Riley said. “The math they apply to the game is second to none.”

The game-play features that contribute to Buffalo’s popularity include:

• A bonus within a bonus. Receive three coins on the first three reels of the game and bonus spins are unlocked. Get more coins on those free spins and more free spins are awarded.

“One of the things players say they really love is the bonus retrigger,” said Matt Wilson, director of marketing and sales at Aristocrat. “They like the ability to accumulate more free games along the way.”

• Reel power. On many slot machines, symbols had to line up for players to win. Not so on Buffalo. As long as the correct symbols appear anywhere on consecutive reels, starting from the farthest left, there’s a payoff.

• Multipliers that multiply each other. When a 2x symbol appears as part of a winning spin, the win doubles. When a 3x symbol comes up, it triples. But when two or more 2x or 3x symbols pop up, they multiply each other to crank up the win by a multiple of six. It’s possible to receive three 3x symbols to multiply the win 27 times.

“The wins are done in a way that they generally come in the bonus feature of the game,” Riley said. “When you hit the bonus feature, there’s almost like a punch-the-fist-in-the-air moment because there’s a good chance you’ll have a big win.”

Riley and Wilson said the game’s graphics and audio — such as a loud stampeding noise when buffaloes appear on the reels and phrases “You little devil!” that pop up on the screen when a player wins — add to its appeal.

“In terms of familiarity, the stampeding buffalo sound, wild animal sounds and eagle sound are on par with the classic ringing noise of a slot machine,” Riley said. “If you walk through a casino and hear them, you’ll know it’s a Buffalo machine.”

The look, sound and play features add up to a game that Wilson describes as an “evergreen,” a franchise platform that will continue to spawn new versions.

“There are a lot of games that have a short lifetime,” Wilson said. “You see that a lot in the licensed gaming space. Games like ‘Big Bang Theory’ or ‘Game of Thrones’ or Britney Spears ... those tend to be shorter in life cycle. But with Buffalo, people play it day after day, week after week, year after year. They’ve really fallen in love with the way the game plays.”