What is a game? Evolution embedded play into the very fabric of being human, so this is a question that has been pondered since the dawn of man. It may be somewhat baffling, then, that we are still unable to reach a consensus.
Searching the web for the “definition of a game” will unearth many different explanations, each described by someone who sees games in a disparate context. The more diverse definitions you read, the more it becomes clear that “game” is one of those words that’s overloaded with meaning. If you consider that we derive what a game is from our own personal perception of play, it’s not surprising that there are as many definitions as there are individuals.
The flexibility of the term becomes a problem if you want to analyse an existing game, or create a new one. In order to design a game, it’s essential to understand the building blocks at your disposal. We can model a game in an infinite number of ways, all different, and all valid. But to be useful, a model must be complete, whilst remaining simple. It needs to be elegant.
While at this year’s PAX East I attended a panel presented by the creators of the GeekNights podcast, Brandon DeCoster and Scott Rubin. It was called “Beyond Candyland”, and sought to explore the theory behind the best German-style board games. They identified “Decision” as the distinguishing factor between games rooted in “Randomness”, like Monopoly or Trouble, and games of skill, like Puerto Rico or Dominion.
Both Randomness and Decision can determine who will win a game, as an event of either will alter the probability space of the game yet to be played. The difference is, you have complete control over the decisions you make, and can take gratification from your performance if you’re victorious through Decision. This is why we favour games that are more heavily weighted towards Decision over Randomness.
As well as Randomness and Decision, the GeekNights duo completed their model of a board game with “Psychology”. Psychology consists of the elements of a game that can not mathematically change the outcome, but augment the rules, like story. A player could choose to completely ignore the Psychology in a game, as it does not alter the probabilistic outcome of the decisions they can make. Poker is an example of a game that is almost pure Psychology. The cards you are dealt are determined through Randomness, and the probability of your hand winning against an arbitrary number of hidden hands is a solved problem. In theory you should only bet on hands with a probability of winning of more than half, so the Decision is made for you. Poker would be a pretty boring game if everybody followed this strategy, simply becoming a game of the luck of the draw. The fun of Poker is in reading and bluffing your opponents, trying to beat the odds. It is a game of accruing or falsifying information outside of the rules of play, which is achieved by reading and influencing human Psychology.
Randomness, Decision and Psychology comprise an elegant model to describe board games, but it needs a bit of work to be able to be applied generally to all games. Brandon and Scott observed that if you add Physiology as a fourth component, we are able to extend the model to include sports. They proposed that when a game rewards dexterity, strength, speed or stamina, it becomes a sport, and that perhaps videogames can be considered sports. I would draw a semantic line between videogames and sports, but agree that both are categories of games that can be classified by this simple, four-axis model.
The model is intuitively complete. All human faculties are addressed, any rule system can be specified, and we can describe all environments in which a game can be played. We now have an elegant model for the entire universe of games. Every game can be constructed from four components, and four components only: Randomness, Decision, Psychology and Physiology. This is an incredibly powerful observation, as it gives us a vocabulary we can use to accurately describe a game and compare it with any other game.
I’ve dubbed this model “The Quad”, and find it particularly useful when dissecting videogames. It’s a common crutch to say that you like a game because it’s fun. However, fun only describes what you feel when your body produces the chemicals to reward achievement. In order to understand how this state of elation is induced, The Quad can be used to identify which aspects of a game lead to you having fun. You can then look for these components in other games, or aim to recreate them in your own.
To summarise, the four elements of The Quad are:
Psychology
The aspects of a game that do not form a part of the rules, and so do not directly influence the outcome. They can have an indirect effect however, if the the player chooses to let them prejudice their decisions. These aspects can include story, character, and environmental themes.
Decision
The rules of a game whose execution are governed by player decision. The probability space of the remaining game is tangibly altered by the branches of its decision tree the player chooses to navigate. That is, the chance of a player winning or losing a game perceptibly changes with their choices.
Randomness
These are the parts of a game’s decision tree that are traversed randomly, without player input. The probability of one decision occurring over another is either specified when the game is created, or is seeded by a dynamic source during play.
Physiology
This describes the portion of a game whose outcome is influenced by the player’s physical ability. The chances of winning or losing are impacted by a player’s dexterity, strength, speed or stamina.
Let’s consider the practical application of this model to a game that a large number of contemporary titles are based on: Quake. Quake’s core gameplay requires the player to position and orientate a 3D camera, and fire a variety of projectiles along that camera’s line of sight. The targets given to the player in the game comprise of either other players or enemy controlled AI. We can break down the sequence of events in a typical piece of play to see which aspects of The Quad Quake is built from.
First, the player must decide where to position their camera to best target their opposition. This decision will be affected by the player’s memory of the map, and the dynamic information that’s being fed to them through the display and speakers. Once a decision has been made, the player must execute the correct sequence of inputs to move the camera, and release their projectile. Their success will be determined by the appropriateness of their original decision, and the speed and accuracy of their execution. The same measure of success is applied to the player’s opponents, and the winner is calculated in a straight comparison.
Decisions made in Quake can dramatically alter the result of an encounter, but do not trump a player’s superior dexterity. Good decisions alone can not overcome an opponent’s dominance of Physiology. This is mainly because the various guns in Quake require more than one hit to kill an opponent. Although making the superior tactical choice allows you to position yourself to fire the first shot in an exchange, as soon as you do so, your location is revealed, and your initial advantage gives way to who can land the most subsequent hits. Quick reactions and the accurate execution of prescribed firing patterns will dictate the result from the opening salvo. It’s interesting to note that this equation is turned on its head in other games of the genre, like Counter-Strike, where the increased power of the weapons makes landing the first hit more influential.
As well as Decision and Physiology, we must consider the other two elements of The Quad: Randomness and Psychology.
Randomness governs very little in Quake. There may be a slight variation in the spread and damage of a weapon’s effect, but the importance of this in a battle is superseded by Decision and Physiology. The only significantly random aspect of the game is in competitive multiplayer, where the opposition’s skill level is unknown until the time of play. Although this can be frustrating if faced with an inappropriately superior foe, the continually changing experience of these varying encounters results in longevity.
id Software employed sparse Psychology in Quake, as it had done in the Doom series that went before it. Without any notable storyline, context is given through the visualisation of your camera as a gun, and by presenting identifiably hostile targets to aim at. The lack of Psychology did not diminish Quake’s popularity, but provided an opportunity for other developers to evolve the genre by bulking out this aspect in their games.
By combining all of these observations together, we can conclude that Physiology is the primary influence in Quake, followed closely by Decision. Randomness and Psychology are both present, but are proportionally diminutive.
In order to visualise our analysis we can weight each of these elements subjectively. This allows us to draw a waffle chart, whose shape represents the genre of a game. We’re able to compare this type of diagram to those for other games to determine their similarity.

Other first person shooters would have a very similar chart. As mentioned above, most extensions of the genre concentrate on creating unique Psychology to set themselves apart. These variations have done very well commercially, but for me the most valid successors to Quake innovate through their Decision mechanics. Good examples of this include Counter-Strike and Left 4 Dead. Counter-Strike rewards strategy over dexterity, diminishing the power of a talented run and gunner, and Left 4 Dead dramatically changes your foe, presenting multitudes of weaker targets who can overrun an isolated player. The difference in the balance of Counter-Strike’s Decision and Physiology to Quake’s can be seen when comparing their respective charts.

There are videogames that have a very different shape when mapped with The Quad in this way. To illustrate the visual difference between genres, I’ve created a waffle chart for Guitar Hero. Guitar Hero’s gameplay can be described as requiring a prescribed sequence of buttons to be pushed in time with a piece of music. With minimal Decision to be made, except for discerning when to use Star Power, and no Randomness to speak of, the game would seem to be almost pure Physiology. The twist in Guitar Hero is that it offers the player extremely compelling Psychology, casting them as rock stars. From the licensed music providing the beat, to the heavily stylised visuals and plastic guitar controller, the game works very hard to abstract away from its simple gameplay. Few would argue that the combined experience is not successful. By drawing a chart of Guitar Hero, we can see that it looks considerably different to one of a first person shooter.

Although these “genre maps” are able to quickly portray the proportional influence of each part of The Quad in a game, the perceived success of each aspect is not apparent. However, this information can be conveyed by weighting each area with a score. For instance, Gears of War 2 is a highly acclaimed first person shooter in the same genre as Quake. Below is a chart constructed in the same way as we have seen above.

Notice the Decision, Physiology and Randomness lobes (blue, green and yellow) are balanced similarly when compared to Quake’s or Counter Strike’s. Yet the scale of these elements has been considerably reduced by the notable increase in weight of Psychology. This is due to the effort afforded to the visualisation, characterisation and depth of the world in Gears of War 2 far outstripping that made in either Quake or Counter Strike.
Working with this chart, we can then scale it by an additional “success” factor, or “score”. If we glance at the Metacritic review average for Gears of War 2, it provides a rough scale factor of 93%. Applying this to each of the four elements in the chart results in the below diagram.

Now imagine that instead of using a total score to scale all of the elements, each is assessed and scaled individually. Using the vocabulary of The Quad, these charts can be used to accurately describe a game’s genre at a glance, as well as giving the analyst a method of independently rating the success of each its aspects. The granularity of the information portrayed is not suitable for delivering in-depth analysis, but it’s a considerable improvement over rating a game with a single overall score.
The Quad provides a unified terminology for what we’ve already been communicating in our discussions about videogames. We lose nothing by using the terms Psychology, Decision, Randomness and Physiology in our analysis, as it doesn’t change the subjective nature of it. The benefit is a common language from which we can build and share ideas. To illustrate this I’ve created my own Gears of War 2 review chart, representing my personal reaction to the game.

As you can probably tell, I didn’t really enjoy my time on Sera. My preference is to play something innovative, and Gears of War 2 certainly was not that. These are some of the notes I made when deciding the scale factors to apply to each element:
Psychology
I enjoyed the artwork and visual effects, but found the story hokey, and the stereotypical characters bland.
Decision
I was disappointed with the variety of tactics that I had to apply during the game. Each arena had obviously optimal locations from which to fire obviously preferred weapons. The set pieces could be approached in a similar manner throughout, with no incentive to change tactics. Ultimately, the majority of the depth of Decision in Gears of War 2 had already been explored in the original game.
Randomness
The online matchmaking was competent at grouping me with similarly skilled opponents, but was not as good as Halo 3’s implementation.
Physiology
The controls gave me a wide range of options to manoeuvre in-game, including an excellent cover mechanic. My own movements were accurately translated to my avatar’s movements, and the reward for being more dexterous than my opponents was satisfying. I enjoyed the conflict between having to watch the arena in front of me, and switching my attention to the reload gauge positioned at the edge of the GUI.
My bias towards games that introduce interesting and varied Decision makes my chart significantly different to the Metacritic chart. We could interpret this as the average contributor to Metacritic finding a game’s Psychology more important than I do, and having a reduced requirement for depth of Decision. Of course, they may have simply enjoyed what was in the game more than I did; it’s difficult to tell from just a headline number.
I hope I’ve shown that if we start using The Quad to describe videogames and display our analysis with more transparency, then the quality of our communication will be improved. We all have an interest in understanding why we like or dislike a game. Armed with this knowledge, we’ll spend less money on games that we won’t like, and spend more of our precious time with the ones that we will.
Vocabulary begets understanding, understanding begets discourse, and discourse begets progress.
Jeffrey Sheen is the founder of London-based Stargazy Studios. His newly-formed indie one-man band is currently developing Huscarls, X-COM and Final Fight’s illegitimate love child. Combining A-Team style welding and a design nous built up over decades of play, Stargazy Studio’s mission is to create new, genre-bending games for an audience hungry for innovation.
www.StargazyStudios.com
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(2 votes, average: 4.00 out of 5)



Thanks. Great article. The only thing I disagree with is your GOW2 review
. I will try to use this in our next design.