Modern casino slot machine games are controlled by computer software, and the win %s are pre-programmed into the computer software.
Casino slot machines have Random Number Generators which are constantly generating combos, even when the machine is not active.
Running in sync with the RNG of the casino slot machine is the payout rate %.
The payout percent controls how much the slot machine will payout, for example the pay % might be ninety per cent, which means the slot machine game will pay out ninety per cent of all the bets played, and the casino only gets to keep ten per cent.
This does not mean that for every time you bet 10 credits you will receive nine in return – where is the fun … thrill in that? Instead, the casino one arm bandit will not payout for a bit, and then suddenly start up a hot streak and you might catch the big jackpot.
The profit percentages will very likely vary between the differing games and several of the most common casinos, for example Golden Online Casino, which provides a payment of up to 95 percent!
Hence, in essence, the slot machine game takes all the funds played into it and pays it out to some privileged winners. The casino only gets to keep a fairly minute percentage of all the wagers made.
The casino slot machine software controls every single part of the machine, from the blinking lights to the spinning of the reels.
When you hit spin on the slot machine game, a combination is set up by the RNG which is linked to the pictures on the reel.