Modern casino slot games are controlled by computer software, and the win %s are pre-programmed into the gaming software.
Casino slot machines have Random Number Generators which are constantly generating combinations, even when the slot machine game is not currently being played.
Running side by side with the RNG of the casino slot machine is the pay out rate percentage.
The payout per cent controls how much the one-armed bandit will pay, for eg the pay percent might be ninety percent, which means the slot game will pay out ninety percent of all the stakes played, and the casino gets to keep ten percent.
This really does not mean that every time you bet 10 credits you will receive nine in return – where is the fun and exhilaration in that? Instead, the casino slot machine game just will not payout for a bit, and then suddenly start up a hot streak and you might catch the big pot prize.
The pay off percentages most likely will vary between the differing games and several of the very popular casinos, e.g. Golden Online Casino, which puts forth a payment of up to 95 per cent!
Therefore, in essence, the one-armed bandit takes all the money played into it and pays it out to a number of lucky winners. The casino only gets to keep a relatively low per cent of all the bets allotted.
The casino slot software controls any part of the machine, from the blinking lights to the circulating of the reels.
When you hit spin on the slot machine, a combination is formed by the RNG which connects with the pictures on the reel.