Games

How a slot decides, and why the reels are the last thing to know

The reels of an online slot spin for a second or two, and by the time they start the outcome has already been decided. Understanding that single fact, and the machinery behind it, changes the way a screen full of symbols reads, and it explains most of what slots do to the people who play them.

The generator, and the moment of decision

At the heart of every online slot is a "random number generator" (software that produces an endless stream of unpredictable numbers), and the result of a spin is the number drawn at the instant the button is pressed. The game translates that number into positions on the reels and then plays an animation that shows them stopping (a second or two of theatre), which is why nothing you do after pressing the button, and nothing the reels appear to do, can change the result.

The generator is the part of the game that independent testing laboratories examine on behalf of regulators, in Alberta as in other regulated markets, and it has no memory of what came before. A spin after ten losses is as likely to win as a spin after ten wins, the first fact to recall when a game seems "due" to pay!

Reels, lines and ways

The reels are a way of presenting the result, while their arrangement decides how a result is read. A classic slot pays on "paylines" (fixed paths across the reels, such as the twenty-five that Wolf Gold uses), a "ways" slot pays on any adjacent combination from left to right (up to 200,704 in Buffalo King Megaways), and a "pays anywhere" slot counts matching symbols wherever they land, as Gates of Olympus does.

Behind the visible reels (the "virtual reel", in the trade's language) sits a list of positions that is usually much longer than the strip we see, and the symbols on it are not equally common. That is how a game can make the top symbol rare and the low card symbols frequent; it is also how a near miss can appear far more often than the odds of the actual win would suggest.

Volatility: how the return arrives

Two games with the same "return to player" can feel different, and the difference is "volatility" (how the return splits between frequent small wins and rare large ones). A low-volatility game pays often and modestly, while a high-volatility game (Buffalo King Megaways is labelled high) pays rarely and sometimes heavily, with long dry spells in between; the average is the same, the evening is not.

The labels are the providers' own, since no standard exists. One game that we played called itself "medium", another printed four out of five on its maker's scale, and a third printed no label at all, so we would read the label as a hint and the "paytable" as the evidence (the gap between the top prize and the ordinary wins says more than any adjective).

Features: free spins, tumbles and buys

Most modern slots add "features" to the base game, in one form or another: free spins started by scatter symbols, tumbles that replace winning symbols with new ones, multipliers that grow a win, and, in some games, the option to buy a feature outright. These features carry a large share of the game's total return, which is why a session without them usually looks like a slow loss.

A feature is not a gift. The cost of the free spins is built, in our view less visibly than it should be, into the return of the whole game, and buying them at a fixed price changes how quickly the money moves rather than how much of it comes back when the session ends (as the rules of Buffalo King Megaways show, with three returns for three ways of playing).

The near miss and the disguised loss

Two effects deserve a name, because they are where the screen and the arithmetic part company. A "near miss" is a result that looks close to a big win (two jackpot symbols and a third just above the line), and a "loss disguised as a win" is a payout smaller than the stake, presented with the lights and sounds of a win.

Researchers have studied both; their effect on how players remember a session is real. In our own session of Gates of Olympus the screen announced a win of 1.60 on a spin that cost 2.00, and in Wolf Gold five moons sat one short of the six that start the feature: neither was progress, and both looked like it at the time.

What a player actually controls

You control the stake, the time and the moment when you stop, and nothing else in the game (the rest is the generator's). The most useful tools are the ones that registered sites in Alberta must offer, the deposit, loss and time limits set in the account, ideally before the first spin, and the province's self-exclusion for anyone who wants a firmer barrier than any limit.

The return itself is explained on return to player, and jackpots on progressive jackpots. The seven games that we played, with their screens and the figures from their rules, are on the games page. If slots have stopped being entertainment, the services on where to find help are free and open at any hour.

By the Alberta Casinos Online editorial team · Last updated: November 13, 2026 · Online since 2026