Every game mixes chance and choice
Games differ in how much of the outcome is decided by randomness and how much is decided by what the players do. Probability describes the first part. Strategy, skill and decision-making make up the second.
Looking at where a game puts its randomness explains much about how it feels to play. Too little chance and the same stronger player wins almost every time. Too much and choices stop mattering. Designers tune the mix to suit the audience and the experience they want.
Three broad types of game
Pure choice, no chance. Chess and draughts have no dice and no hidden shuffled cards. Both players see everything, and the result depends on decisions. Probability plays little role in the rules, though a player might still estimate what an opponent is likely to do.
Pure chance, little or no choice. A game of snakes-and-ladders style race with a single die often gives players no real decisions. The roll decides everything, so the result of each game is mostly a matter of probability. These games can work well for young children for exactly that reason: everyone has a fair shot.
A blend. Most popular games sit between the extremes. Backgammon uses dice to decide what moves are available, and the player then chooses how to use them. Poker deals cards by chance, and players decide how to bet. Many modern board and video games combine a random element with options for the player.
Where randomness enters: before or after a choice
A useful way to think about game design is to ask when the random element happens relative to the player’s decision.
- Randomness before the decision: the player sees the roll, the draw or the hand, then chooses what to do. Backgammon works this way, and so do card games where you see your hand before playing. Players feel they are using skill to make the best of what they were given.
- Randomness after the decision: the player chooses first, then chance decides how well it works. A strategy game where an attack succeeds with a stated hit chance is an example. Players feel the pain of a bad roll more strongly here, because they made a plan that was undone.
Neither is better in general. The first tends to reward skill in adapting, and the second tends to create tension and surprise. The way games present these numbers to players is a topic of its own under displayed percentages.
Quantifying the luck
It is possible to put numbers on the role of chance. Compare two simple dice mechanics:
- Roll one six-sided die and the higher roller wins. Every number from 1 to 6 is equally likely, so the result is swingy and a player behind by one point can still win easily.
- Roll two dice and add them. Totals cluster around 7, since more combinations produce them. The result is less spread out relative to its range, so the outcomes feel steadier. The shape behind this effect is discussed in two-dice sums.
Averaging more random events together usually makes the overall result more predictable, even though each individual event remains uncertain. That is why a game with many small random events tends to reward the better player more reliably than a game decided by one big roll. The wider conversation about whether results come from chance or ability is under luck versus skill.
Tools designers use to adjust chance
Designers have several ways to change the role of probability without removing it:
- Choice of randomizer. Dice, spinners, shuffled cards and drawn tokens all have different shapes of chance. A deck, for example, guarantees that each card appears once per pass, while dice have no memory. Choosing between them is covered under randomizer choice.
- Catch-up mechanics. Rules that help trailing players keep the game exciting, a topic explored under catch-up mechanics. They reduce the influence of early luck.
- Mitigation. Allowing re-rolls, hand sizes bigger than the number of plays, or choices between several options gives players ways to manage bad luck.
- Hidden adjustments. In video games, the software may not use raw randomness at all, which is explained in game randomness.
Real-money games are different
Games played for money are a special case. The rules are normally set so that the operator keeps a margin, known as the house edge, and that means the average result for players over many plays is a loss. Skill can matter in some such games, but chance still creates large swings from session to session, and nothing guarantees a profit. This article is about understanding how games are built, not about finding an advantage. If gambling stops being fun or starts to cause problems, a local support service can help.
Questions to ask about any game
- What is decided by chance, and what by player choice?
- Does the randomness arrive before or after the choice?
- How many random events add up to a final result?
- What rules reduce the effect of an unlucky run?
- Are the odds visible, hidden or only approximately shown?
Answering these gives a good picture of how probability shapes the game, and of how much a player can influence the result.