A lot has been written about the honesty of land-based slot machines. An excellent article by Steve Bourie is titled, “Are Slot Machines Honest?” and originally appeared in the 1999 American Casino Guide. (It can be found online by searching for the title in Google or Yahoo!.) Physical, land-based slot machines have a lot of “variations” (being polite) than can deceive the player. Of course, they are all illegal and do not happen. But read the article, closely.
On the other hand, online casino slots use an electronic “random number generator” or RNG, operating inside a very large computer program that manages the game graphics, the player accounts of those who join the game, the statistics of every hand played, and much more. The random number generator is hard-coded software instructions that do not change. There is no “sense switch” (see the Bourie article) that can be flipped to give players worse odds. Regarding control parameters, each use of the RNG is the same as the last use, and will be the same as the next use. The numbers will come out randomly, but the pattern of randomness never changes. This is a true advantage of software-based online casino slots.
Land-based slot machines can also have payout percentages as low as 83%, which is not true with online casino slots. In online gaming, each machine has the same winning percentage as the other machines. You can see the payout percentages for many online gaming sites, and you will see that it rarely drops below 95% – that is, the house makes a 5% profit, on the average. In fact, most casinos can document that their payout percentages are in the 97% – 98% range. This means that you can spend an hour, gamble your $100 stake about 3 times, and on the average it will cost you $7.50. But players don’t gamble to be average: the true reward is the high-paying win. And the high-paying win is balanced, of course, by a number of players who lose and finance that win.
So are online casino slots fair? Yes, they clearly are. The software that operates the games is tested regularly by independent testing laboratories (look for logos at the bottom of the casino website), and no game is individually controllable to be biased. That is a far cry from the situation with land-based slot machines, appropriately called “one-armed bandits”.