Decision-based Gameplay Design

Introduction

In order to develop a useful understanding of a system, one must know how the system works internally, at the lowest level. Even an exhaustive memorization of every stimulus and response associated with that system is weak compared to an understanding of the underlying elements that cause a system to respond the way it does. One must fully understand the smaller elements that make up the system and how they interact before one can fully predict the overlying system. This is why chemists try to understand how atoms interact, instead of just listing what happens when you mix various chemicals. The designer of videogames needs to understand gaming in the same way.

In this article I'll attempt to break down and expose one of the key elements that exists at the lowest level of most good videogame experiences. It is useful to break down our understanding of videogame fun to the most basic level because if we can achieve that, we gain a simpler, more generalized understanding of video gaming that transcends boundaries between genres or styles. Principles that apply at the lowest level aren't confined to a genre. Thus, what made Half-Life fun was the same thing that made Bejeweled fun, which was also the same thing that made Starcraft fun. These games may seem totally different in play style, complexity, and theme, but all three were popular and very similar in one of the most fundamental aspects of interactive games. That is, they all presented the player with a continuous stream of difficult and interesting decisions.

Decisions are ultimately what make a game. The only thing that separates gaming from books, movies, plays, and music is the element of decision-making. None of these traditional entertainment forms afford the entertainee any capacity to make a decision about anything. Books, plays and movies are still unarguably superior to games in their ability to tell complex, interesting stories. Few videogames could even be reasonably argued to have come close to a good movie or book in terms of character development, plot and thematic development. In terms of visual eye candy, movies still blow videogames out of the water because of the power of prerendering, hand-optimized shot-by-shot composition, and custom-chosen viewing angles. The question becomes, if games are so inferior in story, and visuals, then why does anyone bother playing them?

There are several answers to this question, but I'm going to focus on one. The ace that gaming has up its sleeve is that it gives the player opportunities to make decisions and then observe the results of those choices in a consequence-free zone. This is why people play videogames instead of watching movies. Almost all good games do this very well.

Often people will mistakenly believe that the concept of decision only includes big, branching storyline-type choices, like those that appear at branching story paths. Not so. The important decision making in videogames occurs extremely frequently and is concerned with relatively small changes to the game world. Decisions like whether to reload a weapon or instead wait another one second to re-evaluate the situation are what should concern game designers.

Analysis of the best decision-making games reveals some interesting correlations between game fun and the type of decisions presented to the player. These correlations are:

Let's look at these two in detail.

Aspects of Good Gameplay Decisions

1. Difficult Decisions

It should be obvious that decision-making isn't the only thing that makes game fun. Games can and do still have stories or eye candy that provide an element of entertainment. In order to analyze decision-making gameplay free of intellectual interference from other sources of fun, we'll look at a group of games which include the least amount of these other factors. Multiplayer competitive games typically have no story, and some of the most popular ones are ugly enough to make a small child cry. These traits make them excellent subjects for decision/fun analysis.

Multiplayer real time strategy games in particular are excellent examples. At all times, the player must decide what his spending priorities are, where to focus his attention, how many resources to put into scouting, defense, offense, economic development, and so on. RTS games provide the player with a constant stream of difficult and interesting decisions by ensuring that the player must be constantly compromising. Each decision always offers at least two strongly competing options, which makes it difficult, and thus, interesting. Many decision points present far more than two possible options, which make them even more challenging.

A common example of this type of excellent decision is one which all RTS players make thousands of time per game: what should I look at next? Common possible options include:

Very frequently many of these options are vying strongly for attention, which makes this a very difficult choice. A player may be micromanaging a battle, but his economy will be dying from lack of attention. If he leaves the battle, however, his troops will be at a disadvantage and vulnerable, but then again, his better stewardship of his economy may allow him to better reinforce his army, or to fight another battle another day. The simple decisions as to whether to check one's base is one that will be influenced by too many factors to list here. At high levels of play, good attention management becomes as much a skill as anything else. The richness and temporal density of the stream of decisions presented to the player is what has made RTS games so popular.

Multi-player first-person shooter games like Counter-Strike are also excellent examples of decision-making gameplay. Like RTS games, they offer the player a continuous series of difficult decisions, and each decision has many equally-weighted sides. Common decisions include the following:

The specific circumstances of each individual match make every instance of these decisions unique. This uniqueness of every decision is what makes these games fun over the long term. Uniqueness is a sub-property of difficult decisions. In order for a decision to be difficult, it must be sufficiently unique. Each decision cannot have been made before; otherwise it is no longer a decision. If you present the player with exactly the same situation over and over, he will learn what the best thing to do is and thus the choice becomes easy. Easy choices are not really choices at all, any more than presenting an FPS player with a cliff edge is a decision point. The decision not to jump is a rather easy one, and thus not a decision at all.

Decisions must be unique to be difficult. The beauty of multiplayer games is that they can present millions of possible situations because there are so many possible interactions and situations between human players, and because human begins have so many unique, individual traits that make each opponent different. Interactions between multiple players add exponentially more complexity to the situation.

So, in order for a decision to be fun, it must be difficult, and in order to be difficult it must also be unique.

2. Tangible and Obvious Results

The process of designing a decision opportunity is not all a designer needs to do. The aftermath of a decision-making event is important as well. A player's enjoyment of a game can be enhanced greatly by the amount and type of feedback that they receive from the game as a result of their decisions. This is why impressive explosion, gunfire and blood effects are important in FPS games, or why good puzzle games often include flashy effects to mark important events. Seeing an enemy die spectacularly is a reward for a decision well made, as is hearing the trumpet call at the end of a puzzle game well won.

Each decision can thus be evaluated not only on its difficulty and uniqueness, but by the power of the feedback that results from it. The same difficult, unique choice can be gratifying and interesting, or rather pedestrian based on the strength and tangibility of the feedback it produces.

There are many ways of delivering feedback to the player: visual, auditory, narrative, constructive, and so on. Some simple examples of feedback are the flashy effects that appear in puzzle games when the player makes points, the blood sprays in FPS games (though there is also a strong element of role-playing here), the accumulation of wealth or valuable items or character traits, the forward movement of a story or formation of an alliance, and so on. Feedback design is a well-developed and generally well-understood field of game design.

Multiplayer games, interestingly, have an inherent advantage when it comes to rewarding a player's good decision. When someone else is on the other end of the line, winning a conflict comes with automatic positive feedback. Defeating a real live human being in any kind of contest, even anonymously over the internet, is a reward in itself. Good feelings associated with beating human opponents are a well-developed part of human biology. This, in addition to the uniqueness of human opponents, is one of the things that have made multiplayer gaming so compelling.

Examples

Examples are always useful, so I'm going to give some, just to elucidate how often decisions have to be made in a good game.

My first example will be a round of a decision-laden game that many people are familiar with: Counter-Strike. Our player, Bob, is playing in a 5-on-5 game as a terrorist on the level de_aztec.

Bob joins the game. He chooses to join the terrorist team. As the current round finishes, he gathers some basic information about the game. The scoreboard tells him which team is winning, the winning record of the teams, and which players are best. The terrorists have been losing. He notices that a counter-terrorist player named Charlie is dominating the central open area of the map with the powerful AWP sniper rifle. Charlie has a lot of kills, which means he is a particularly good player and has likely been using the AWP in the open area for some time, with a lot of success.

Charlie finally kills the last terrorist and the next round begins. Bob quickly analyzes the situation and must make a decision as to his general strategy and chosen route for the next round. While making this decision, he factors in his own team's apparent lack of counter-sniping ability, his inability to afford a flashbang or powerful weapon, Charlie's likely future presence covering the main open area, his own particularly high skill level at close combat, and a variety of other factors. After one second, Bob decides to take the rightmost route across the bridge, avoiding confrontation with Charlie altogether and placing him in an area that hopefully allows him to use his close-quarters combat skills. His most difficult task will be making it across the bridge alive, since he can't afford long-range weaponry. Once he is across the bridge he will be in a close-quarters-combat area, where he will have a skill advantage. The risk of crossing the bridge is significant, but Bob's alternatives are probably worse.

Bob spawns. He can only afford basic armor and an MP5 submachine gun - a cheap and utilitarian weapon that is useless at long range. His team moves, and he moves with it. He is at the back of the group. Three members of his team go through the door to the open central area. Bob watches the death announcement as Charlie immediately kills one of them with the AWP. Bob expects the other two to die. However, just as Bob is about to split off towards the bridge route, Charlie is unexpectedly killed by Bob's teammate.

Circumstances have changed. Bob must immediately re-evaluate the situation. He is accompanied by only one other team member in his assault on the bridge; less than he expected, which will make it harder to make it across the bridge into his preferred close-combat territory. Also, Charlie's sniping skills have been removed from the equation, making the open central area a much more attractive route. There is also the chance that Bob's dead teammate dropped a weapon superior to his own. Bob makes the choice to abandon the bridge route and join his teammates in the open area.

He passes through the large double doors into the open area. His two teammates are 20 meters away, in open territory, as is the dead teammate. Indeed, the dead friendly dropped an AK-47, a much superior weapon to Bob's MP5. The teammates come under weapons fire from an enemy position on the other side of the area.

Bob must now decide whether he wants to attempt to retrieve the AK-47 lying out in open territory. This is a complex decision, and Bob will make it in less than one second. Bob must think relatively far ahead to consider the various possible outcomes to either side of this decision. If he doesn't get the AK-47, and his teammates die without his support, he is in a very disadvantaged position, since he will be fighting at most likely 4 on 2 or 3 on 2, with only an MP5. However, if his teammates win the engagement, Bob can simply grab the AK-47 in safety after the fighting is over. He will be able to support the team as they plant a bomb in the open area, and will have a more powerful weapon for free if he survives into the next round.

I'll leave it to the reader to consider what might also happen if one teammate dies and the other flees in the opposite direction, if one or both flee towards Bob, if a teammate makes it close to Bob and dies, leaving a weapon near Bob, and so on.

There are obviously a lot of possibilities here, and this is a situation that Bob doesn't know much about. If Bob was fighting in a clan match with friends he knew well, the system would be much more complex since his decisions would take into account the specific skills and behavior traits of each of his teammates, and, in case he had studied the other team's record, perhaps his opponents. All Bob really knew about this match was that his team was losing, and that Charlie was a good sniper. Imagine the exponential increase in complexity had the match involved nine known friends and opponents, with pre-discussed tactics and strategies.

I hope that this abbreviated discussion of the first 15 seconds of a simple Counter-Strike match, not even including any direct contact with the enemy, has made you appreciate just how complex and numerous the decisions in a good game are. Also, note that the last two decisions, whether to change routes, and whether to grab the fallen AK47, happen within 3 or 4 seconds of each other, and are both made within one second. Both decisions, as obvious above, are quite complex.

Counter-Strike is a very good game when it comes to decision generation. Any game of Counter-Strike, analyzed deeply, becomes a series of extremely complex decisions made at intervals generally between half a second and five seconds.

Decision Recognition, Evaluation, and Design

Game designers need to not only understand how decisions create a computer gaming experience, but also need to be able to create an experience that includes lots of unique, difficult decisions with strong feedback. Creating good decision-based games requires three abilities: The ability to recognize a decision point, the ability to evaluate how fun a decision is, and the ability to design fun decision-making play without compromising other aspects of the game (i.e. without requiring lots of new assets or making the game too complex and difficult to learn).

1. Recognition

The first step is to recognize all the decision points. This is not as easy as it sounds, especially in a well-designed game which presents decisions very frequently. When reading a design document, try to imagine playing the game. You are essentially emulating the gameplay in a very inaccurate way using your brain. Think about what's going on, what you know, what you don't know, the challenges being presented, and the rewards sought. Go through the gameplay, step-by-step, instead of imagining the gameplay in an abstract way, or only considering the most interesting parts. Skip nothing; what you skip will most likely be a boring decision void. Get a feel for how much real time everything is taking. Finally, while doing all of this, you must recognize the decision points as the design presents them. Develop a feel for how often decision points come up. If your game is based on gameplay, but isn't presenting a lot of decisions, you have a problem and you need to re-evaluate some aspects of your design.

The same process can be more easily applied to a game that is actually functioning, since one just has to play the game with an eye on the choices they themselves are making. Committed designers will pause the game whenever a decision presents itself and note it on paper. Notice how often you are pausing the game. It should be very often.

2. Evaluation

Once you have an idea of how many decisions the player is making, and what they are, you can begin by evaluating those decisions. Consider each decision point separately, and determine how difficult each decision is, and how likely it is to recur. If the decision is easy it is worth little. If it recurs a lot, it becomes easy and thus is worth little.

Each decision must also be evaluated in terms of cost of implementation. To implement a decision system takes a certain amount of time spent by members of the development team. Many decision-creating systems also suck up CPU cycles. Another very important cost that can be associated with a decision system is the complexity that it adds to the game. A game element that requires the player to know something, or have some skill, or at worst, bind and memorize a key or virtual button, is a game element that is costing something.

One example of a bad system in this regard is one that thankfully never made it into a game. During part of Half-Life's development, the player had the ability to put on or take off his HEV suit helmet. The decision as to whether to change the helmet was generally not very difficult, so it was worth little. This system required coding, code maintenance, and a key bind and memorization as well. Half-Life's designers wisely evaluated the helmet system and tossed it since it wasn't performing from a cost/benefit analysis.

An example of a costly system that was worth the cost can be found in any FPS game: the ability to fire a weapon. Players must bind keys to select weapons, fire one or more fire modes, perhaps to reload or change something about their weapon. They must also learn to shoot. Designers need to model and animate guns from first and third person, code them, test them, balance them, and so on. This is a very costly system. However, it is worth the cost because of how many ways the designers can and did use the player's ability to fire a weapon to create decision points.

Designers need to carefully evaluate decision costs and must have the discipline to cut game elements that are costing more than they are worth in terms of interesting decision creation.

3. Design

Designing decisions is the trickiest part of the process, because the very nature of good decisions is that they cannot be directly defined. Decisions placed directly in the game will either recur too often and become non-decisions, or will only be seen a small number of times. An example of a directly-placed decision would be a situation where a player is presented with two separate attack routes which were both explicitly designed. One route will inevitably be more advantageous for any given player's playing style. Once the player tries both routes, he learns which route is better. Thus, if the exact same routes are presented to him again, this becomes a non-decision, and the player's brain becomes disengaged. All explicitly-designed decision points have this problem of staticity. The solution, of course, is to create a gameplay system that dynamically generates emergent decision points.

The goal with emergent decisions is to avoid explicitly defined decisions, and instead create a set of rules, characters, elements, and interaction rules, with a defined goal, such that interesting decisions will emerge from the system. Let me make this very clear: Game designers should rarely be designing decisions directly. The job of the game designer is to develop gameplay systems that present emergent decisions. Only emergent decisions can be unique over a long period of time. Static decisions cannot be relied on to provide gameplay interest, though it should be noted that they cannot be eliminated altogether.

Designing the dynamic decision-generating system is the game designer's greatest challenge. I'll leave this to another article.

Closing Thoughts

Decision making is not the only thing that makes a game. While a game depending primarily on its interesting decisions can be entertaining, good mainstream titles must also incorporate role-playing, socialization, joy of creation, or any of the many other aspects that make good games. Gamers want to make decisions and see results, but they also want to socialize, imagine themselves as fighter pilots, build gleaming cities, or create powerful personas known throughout the land.

What is unique about decision-making among all these elements is that it is one of a very small set of elements that are unique to gaming. Only forms of entertainment that contain decisions are called "games", including sports, board games, videogames, or even game hunting. One could then say that the opportunity for the player to make decisions is what defines a game distinctly from non-interactive forms of entertainment. The opportunity to give the player decision-making capability is what game designers have and what Steven Spielberg and Tom Clancy wish they had. Understand this opportunity, and use it to its fullest. If decisions aren't part of your game, you should be making a movie.