A Dive Into the History of Game Machine Mechanics
Slot machines might seem pretty straightforward today—click a button, spin the reels, and see what shows up. But the mechanics behind them have gone through some serious changes over the years.
From bulky machines with spinning drums to today’s digital setups with dozens of features, it’s been quite a journey. If you’ve ever played at a free bet casino, you’ve already seen the results of over a century’s worth of development packed into a few clicks on sites like VirginBet.
And while the look and feel have changed, the core idea is the same: a game based entirely on chance, built around symbols lining up in a particular way.
In this article, we take a closer look at how slot machine mechanics have evolved over time. From their earliest mechanical roots to the advanced systems found in today’s online games. Read on to find out more.
Where it began
The first version of a slot machine wasn’t really a “slot” at all—it was a poker-based contraption created by Sittman and Pitt in the 1890s.
It used five mechanical drums with card faces on them. Players would pull a lever and hope to land a decent hand. There weren’t any built-in payouts, so if you won, someone behind the bar had to step in and sort you out.
A few years later, Charles Fey stepped in with something much simpler: three reels, five symbols, and—importantly—an automatic payout system.
His Liberty Bell machine quickly became the template for future slot machines. It’s easy to see how that small change made a big difference. No need for staff involvement, and no delay in getting your prize.
The switch from gears to algorithms
Aside from how they’re built, the big changes to Slot machines have been around how you can win and what happens when you do.
These days, everything is run by a random number generator (RNG). It’s the engine behind every spin, making sure each result is random and not affected by what happened before, or what’s coming next.
This upgrade opened the door for new features that just wouldn’t have been possible with mechanical reels.
Despite all the extras, it’s worth remembering that slot machines still work on a chance basis. Features may add complexity, but at their heart, it’s still about spinning and seeing what lands.
Bonus features became more creative too. Instead of just matching symbols across a line, you might unlock a mini-game, a set of free spins, or a jackpot round. Some games offer multipliers or wild symbols that shift around the reels, adding more variation without changing the underlying chance-based mechanics.
Every one of these additions operates within clearly defined rules, and all are regulated to ensure transparency. The published return-to-player (RTP) rate helps give you an idea of what proportion of stakes is paid back over time—but no feature or system ever guarantees a win.
What next?
Slot mechanics are still evolving. As more people play on mobile, games are being designed with smaller screens and touch controls in mind. Some developers are even exploring more interactive features or live elements, where animations respond in real time.
Even so, the fundamentals haven’t changed. Whether the slot you’re playing has three reels or six, a single payline or multiple features, the spin itself is still determined by a random algorithm—and it’s that consistency that keeps the format fair and regulated.
So while the design might look different, and the features might feel more complex, the core mechanic is as old as the Liberty Bell machine. It’s still all about spinning, waiting, and seeing where the symbols fall.