Clearing up "Can slot machines be hacked?" starts inside the cabinet. A slot machine looks like a game of reels, but what decides every payout is a random number generator working out of sight. The reels, the paylines and the buttons on the screen only show a result that was fixed the moment the spin began. Knowing how that works, from mechanical machines to modern video slots with megaways and bonus rounds, clears up most of what players ask about them.
Paylines on a slot machine are the patterns across the reels that count as a win, from a single middle line on classic games to hundreds on modern ones. Megaways games change the number of symbols on each reel every spin, giving tens of thousands of ways to win. The buttons set the stake and the number of lines. Which type of slot machine is best depends on what a player wants: steady small wins, or large ones that come rarely.
A few questions come up about what happens behind the scenes. When a slot machine is reset after a jackpot or a fault, nothing about its odds changes; the generator keeps running. When a machine malfunctions, the rule printed on most games voids pays and plays, and the logged result settles any dispute. Slot machines cannot be adjusted on the floor without approval and new software. Hacked machines are a rare crime, not a player strategy, and old slot machines are usually scrapped or sold to collectors.
Return to player, the share of stakes paid back across millions of spins, is chosen by the operator and fixed in the game software rather than adjusted between spins.
A random number generator picks the outcome the instant the spin button is pressed; the reels only display a result that is already fixed.
Each spin on a Class II machine is really a round of bingo against other players, and the reels simply present that draw's result in a familiar form.
Free spins, pick features and wheels are games inside the game, funded from the same return to player as ordinary spins rather than from anything extra.
Autoplay runs a chosen number of spins automatically, and limits set on total losses or on a single large win halt it before the count runs out.
A coin passed sensors that checked its size and weight, a lever or button released physical reels, and the stops on each reel decided the symbols.