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Occasional studies from the casebook of gambling, games, risk and regulation
The windmills of my mind: what is a slot game, and why does the law care what it looks like?
Online slot games now carry their own stake limits and their own design rules. Which games are caught depends on a definition which looks at how a game is displayed, and says nothing about how it is played or what harm it may do. This article looks at that definition, and at the odd results it produces.
THE THREE POINTS TO REMEMBER
- An online slots game is a casino game which is a “reel-based game” played online. The test turns on moving or changing images and the arrangement in which they come to rest.
- The definition says nothing about speed of play, size of stakes or harm. It can catch slow and gentle games, and miss fast and hard ones.
- Classify every game against the words of the definition, not its general appearance, and keep a written record of the reasons.
1. Why the definition counts
Since 31 October 2021 the Commission's Remote Gambling and Software Technical Standards (RTS) have imposed specific design rules on online slots, including a minimum speed of play and a ban on autoplay and on features which celebrate a return equal to or less than the stake.
Since 2025 online slots have also been subject to maximum stakes per game cycle, set by the Gambling Act 2005 (Operating Licence Conditions) (Amendment) Regulations 2025 (SI 2025/215). The limit is £5 for players aged 25 or over and £2 for players aged 18 to 24.
Those rules apply to slot games and to no other casino game. Whether a game is a slot game therefore decides how fast it may be played, how much a player may stake on it and which features it may contain. The definition carries a good deal of weight.
2. What the definitions say
The Regulations define an online slots game as a casino game which is a reel-based game and is played online. A reel-based game is one in which:
(a) “moving or changing images or text are displayed by the use of visual representations of reels or other means”; and
(b) “an individual may win a prize or some other opportunity or advantage, as represented by the resulting arrangement of those images or text”.
A “casino game” is defined by s.7(2) of the Act as a game of chance which is not equal chance gaming. Games played against the house are therefore in; games in which players compete on equal terms, such as bingo, are out.
The RTS definition is even shorter: “Casino games of a reel-based type (includes games that have non-traditional reels)”.
Neither definition refers to the length of a game, the amount which can be staked or lost in a given time, the house edge or the volatility of the game. The only test is visual. Something moves, it stops, and the pattern in which it stops tells the player whether there is a win.
3. The windmill problem
Defining a gambling product by the way it looks is rather like regulating mills according to whether they have sails, rather than by what they grind. A windmill and a wind turbine both go round. A water mill does not, but it grinds corn just as well.
The Act itself generally does better. A gaming machine is defined by s.235 by reference to its function: a machine designed or adapted for use by individuals to gamble. Bingo is defined by s.353 as “any version of that game, irrespective of by what name it is described”. That is a circular definition, but at least it looks to the substance of the game and not its decoration.
The slot definition goes the other way. It takes the one feature which everyone associates with a slot machine, the spinning reel, and makes that the test. The policy concern is harm, and in particular fast, repetitive, high-stake play. The definition picks out a picture.
4. A game with a bingo card
The difficulty is well illustrated by hybrid games which combine features of bingo and slots. In one well-known format the player buys a game and is shown a bingo card. On each of a fixed number of turns a row of numbers or symbols is revealed beneath the card, and any matching numbers are marked off. Jokers allow the player to choose which number to mark. Prizes depend on how many lines are completed by the end of the game, and the player may buy additional turns.
A game of this kind is played in a very different way from a traditional slot. A game lasts well over a minute, rather than a few seconds. The player makes choices which affect the result. The attraction is the gradual completion of the card, which is much closer to the experience of bingo than to a series of rapid, separate spins.
However, the row of changing numbers is “moving or changing images”, and the prize depends on the arrangement in which they finish. The game is played against the house, and so it is not equal chance gaming and cannot be bingo. On the Commission's reading, that is the end of the analysis: the game is a slot game. The evidence about how long the game lasts and how people play it is simply irrelevant to the test.
5. Too wide and too narrow
Too wide. Read literally, the words “or other means” extend the definition well beyond reels. A great many casino games display changing images and pay out according to the result. A roulette wheel spins, and the ball comes to rest in a pocket. The Commission's guidance says that roulette and blackjack are not caught, but that is an interpretation of the policy rather than something the words themselves make clear.
Too narrow. At the same time, the definition does nothing to catch games which share the harmful characteristics of slots but not their appearance. Examples include:
(a) crash games, in which a multiplier rises until it stops, which can be played at high stakes with very short cycles;
(b) fast instant-win games, in which panels are revealed in a few seconds; and
(c) the many new formats which designers will produce once they know that reels attract stake limits and other displays do not.
The predictable result is displacement. A rule which limits stakes on games that look like slots creates an incentive to develop fast, high-stake games which look like something else. The players most drawn to hard gaming will follow the product.
6. A better test
In my view the rules would work better if they were attached to the characteristics which the evidence links to harm, whatever the game looks like. Those include:
(a) the length of the game cycle;
(b) the amount which can be staked, and lost, in a given period;
(c) features which encourage continuous or repeated play; and
(d) the volatility of the game.
A test of that kind would treat a slow, choice-based hybrid differently from a three-second slot, and a fast crash game in the same way. It would also remove the incentive to redesign products around the definition rather than around the player.
The Regulations require the Secretary of State to review them at intervals of five years. That review is an opportunity to replace the reel with something which bears some relation to the purpose of the rules.
7. What operators and designers should do
Until the definition changes, operators and game designers have to work with it as it stands. Every casino game should be tested against the words of the Regulations and the RTS, and not against a general impression of whether it looks like a slot. Hybrid formats, and games which use moving images in a novel way, need particular care, because the Commission is likely to read the definition broadly. The reasoning behind each classification should be recorded, together with evidence of how the game is played. A definitive view on any particular game depends on its mechanics, its display, the way prizes are determined and the licence under which it is offered.
Important notice. The views expressed in this article are the personal views of the author and do not necessarily reflect those of Keystone Law or Collova Consulting Ltd. The article is intended as general commentary only. It is not legal advice and should not be relied upon as such. Legal advice depends on the particular facts and circumstances of each case, and specific advice should be obtained before taking, or refraining from, any action in reliance on anything said here. The law is stated as at September 2026. No responsibility is accepted for any loss arising from reliance on this article, and reading it does not create a lawyer and client relationship.