INFR 1330 (2014) Basic Introduction to Game Design

Chance and Skill in Game Design

Cite this article as: Lennart Nacke. (October 15, 2014). Chance and Skill in Game Design. The Acagamic. Retrieved December 10, 2018, from

Welcome to the fifth week of class in the course: Basic Introduction to Game Design. Make sure to read the syllabus and course information before you continue. Today, we are going to discuss chance and skill in game design. This text follows closely from our textbook (Challenges for Game Designers, Chapter 5 and 8). I also take inspiration from Schell’s The Art of Game Design (Chapter 10, pp.150-170) and Adams’s and Rollings’s Fundamentals of Game Design (Chapter 11). However, this is the part when I break free.

Games, which feature meaningful decisions, do not always have to require or evoke skills from a player. Some games operate entirely by chance. Games that rely more heavily on chance than on skill are often found in the context of children’s games or gambling. Why does this difference matter? The player is going to play, play, play, play, play – are they not? Do not shake off the notion of chance too swiftly. Games of chance can be very engaging, because they can allow players of different skill sets to engage in a balanced competition. Games are for everyone; for people, who are used to rolling the dice and people, who like to feel the fear in their enemy’s eyes. Some people even think it is fun to lose and to pretend. However, games of luck in particular seem to feature more attainable goals and are winnable by more people.

On the other hand, games like Tic-Tac-Toe are entirely skill-based and can be mastered, once a player figures out a dominant strategy. See this example lecture for forming a Tic-Tac-Toe strategy via reasoning:


It might seem crazy what I am about to say, but there are several reasons for games to use chance as a game mechanic:

  • The  game designer wants to prevent or delay the player from solving the game.
  • The game designer wants the gameplay to be balanced and competitive for all different kinds of players.
  • Chance can increase the variety of elements in your game system.
  • Chance can help you create dramatic moments in your game.
  • Chance can enhance the decision-making in your game.

On Game Balance

Adams and Rollings describe a balanced game as “fair to the player or players, […] neither too easy nor too hard, and makes the skill of the player the most important factor in determining his success.” A game that is considered well-balanced, therefore, has the following characteristics:

  • The game provides meaningful choices. Several strategies can allow the player to win. There is no dominant winning strategy in the game.
  • Chance does not play a role so great that player skill is irrelevant. A player with more skill should be more successful than a poor player.
  • The game’s level of difficulty should be consistent. The players perceive the challenges in the game as not abrupt and within a reasonable range of their abilities.

In Player-vs-player games, the following characteristics also apply:

  • The players perceive the game as fair.
  • Any player, who falls behind early in the game, gets some opportunity to catch up before the end of the game.
  • The game seldom or never results in a stalemate if the players are of unequal ability.

 Playtesting for luck and skill balance

When balancing games, an important factor to consider is the balance of skill and luck elements in the games. Some of the following are signs indicating that your skill/luck balance might be off:

  • Your players are bored. This is generally a sign of missing interesting decisions in the game and too many luck elements.
  • Your players are only bored when it is not their turn. Your game is likely lacking some strategic elements as none of the things players do during their turn seem to affect other players’ turns.
  • Your players do not become engaged in the game and are confused about what to do. This could be a sign of too many decisions or too much information to process for players.
  • One of your players beats all the other players by a wide margin. This could be an indicator that your game is heavily skill-based and one player has mastered this skill. To keep a game balanced for players with different skill levels, it is important to add some elements of luck to it.

Generally, adding “luck” to a game comes down to adding elements of randomness. In board games, this is often done through dice rolls or shuffling cards. If you find that you are using too many of these random elements, you can replace them by using distinct automated advances (e.g., moving a player token a distinct number of spaces during a turn) or by adding a player decision instead of the random element (e.g., players can choose from a given range of movement options). Player decisions are not just complex thinking decisions at all times, but can also be split-second dexterity-based decisions (twitch skills like hitting notes in Guitar Hero).

Our textbook (Challenges for Game Designers) distinguishes between three types of luck/skill games:

  1. Games of chance. This can be either children’s games or gambling games. These games can often be enhanced by adding twitch and strategic elements to them. Often just the illusion of skill in those games is enough to make them more interesting.
  2. Games of twitch skill. These are games that are focused on a challenge of dexterity. These games tend not to work too well with chance elements, but adding simple tactical options is quite common. Anything that keeps the flow of the game is a possible addition.
  3. Games of strategic skill. These games can feel tense and slow, because they involve a lot of thinking. Adding twitch elements can be a welcome interruption of these long strategic sessions. Many long-winded RPGs feature little twitch mini games (such as lockpicking in Skyrim) to interrupt some of the longer stretches.

Types of Skills

Jesse Schell distinguishes between three main categories of skill in his Art of Game Design book. Keep in mind that many games require a blend of different skills, but these categories provide a starting point:

  1. Physical skills: Skills like dexterity, coordination, strength, and physical endurance. These types of skills are most commonly found in sports games. However, some might argue that the correct keypress and controller sequences found in some esports would also fall into this category.
  2. Mental skills: Skills like observation, memory, and puzzle solving. Often these relate to making interesting decisions in a game, as most interesting decisions are also tactical decisions.
  3. Social skills: Skills like reading an opponent, tricking an opponent, and coordinating with teammates. These relate to a player’s ability to make friends and influence people in a game. They are often tied to a player’s communication skills. This is also commonly seen in team-based sports.

Schell also distinguishes between real skill, which means your actual skill as a human person in controlling the game in a certain way, and virtual skill, which relates to your in-game character’s skill at doing something. Real skills only improve when you work on them, while virtual skills can improve even when your real skill does not improve. In general, Schell suggests making a list of all skills in your game as an exercise to break down your game into skill components.  Finding out what skills you require from your players will make you a better designer.


Chance can make games more fun, because it adds elements of uncertainty to it. Uncertainty equal surprises for players and humans do enjoy surprises. Chance is also related directly to probability in games, and Schell lists ten rules of probability with which game designers should be familiar:

  1. Fractions are decimals are percents. Fractions, decimals, and percents essentially all work the same way and are essentially the same thing: 1/2 = 0.5 = 50%. As humans, we like to express probabilities in percentages.
  2. Zero to one – and that’s it. This concerns, of course, probabilities, which all happen in the space between 0 and 1 (i.e., 100%). Chances like -10% or 110% do not exist when we speak about probabilities in games. If you are trying to calculate the probabilities of your dice rolls and they come up higher than 100, you know that you will need to run your calculation again.
  3. “Looked for” divided by “possible outcomes” equals probability. Probability really means you take the number of times the outcome that you are looking for can (or has) come up and divide this by the number of possible outcomes (in the case that all outcomes are similarly likely) .
  4. Enumerate. Let’s say that you are trying to find the outcomes that you are looking for and it is not as straightforward as the numbers on a D6; a good way of getting to your answer is just to list all the possible outcomes in your scenario. This helps you see patterns and combinations.
  5. In certain cases, OR means ADD. When trying to determine the chances of x or y happening (like drawing certain cards from a deck) and these events are mutually exclusive, you can add the probabilities to get the overall probability of an OR event.
  6. In certain cases, AND means MULTIPLY. When we are looking for the probability of two things happening simultaneously, we can multiply their probabilities. This only works if the two events are NOT mutually exclusive.
  7. One minus “does” equals “doesn’t.” This quite logical as 1 represents a 100% chance of something happening. So, whenever you have calculated the probability of something occurring, you can subtract this number from 1 to find the probability of the opposite event occurring.
  8. The sum of multiple linear random selections is NOT a linear random selection. By linear random selection, we are referring to a random event where all the outcomes have an equal chance of occurring. A die roll is a great example of this. Adding multiple die rolls does not mean that the possible outcomes have an equal chance of occurring. Rolling a die twice means that you have a higher chance of a seven occurring. The possible outcomes of this scenario follow a probability distribution curve (a normal distribution in this case), where the numbers in the middle (6,7,8) have a higher likelihood of coming up.
  9. Roll the die. Schell distinguishes between theoretical probability and practical probability. Theoretical probability is what we have talked about so far. It is what is likely to happen in a general case. However, practical probability accounts for what has already happened. For this you would just roll a die over and over and record the number that you are getting and calculate your probability based on this. Ideally, this probability should approach the theoretical probability with a repeated number of trials. This is also known as the Monte Carlo method.
  10. Geeks love showing off (Gombauld’s law). Schell basically recommends to find a math wiz friend, whenever you are facing a probability problem that you cannot solve on your own. This can also include posting math and probability related questions to mailing lists.

Some important things to remember about chance are (from Adams and Rollings):

  • Use chance sparingly.
  • Use chance in frequent challenges with small risks and rewards.
  • Allow the player to choose actions to use the odds to their advantage.
  • Allow the player to decide how much to risk.

Further Reading

Am I missing something? Write a comment to this post at the very bottom of the page.

  1. Making Sense of Complexity. Brice Fernandes (2014). Gamasutra.
  2. Design in Detail: Changing the Time Between Shots for the Sniper Rifle from 0.5 to 0.7 Seconds for Halo 3. Jaime Griesemer (2010). GDC Vault Video.
  3. On Difficulty Levels. Ben “Yahtzee” Croshaw (2010). Extra Punctuation.
  4. Playing Fair: A Look at Competition in Gaming. Mark Newheiser (2009).
  5. An atomic theory of fun game design. Raph Koster (2012). See also: Grammar of gameplay.
  6. The Mathematical Structure of Possibility. Mark Neyer (2014).

Further Viewing


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