[In an essential design column, originally printed in Game Developer magazine, EA Maxis designer and programmer Soren Johnson (Spore, Civilization IV) shares four major insights from design legend Sid Meier on creating truly good games.]

Most game developers are familiar with Sid Meier's dictum that "a good game is a series of interesting choices."

In fact, my co-columnist Damion Schubert started his recent article on player choice (October 2008) by referencing this famous quote.

However, over the course of his career, Sid has developed a few other general rules of game design, which I heard him discuss many times during my seven years (2000-2007) at his studio, Firaxis Games. As these insights are quite practical lessons for designers, they are also worthy of discussion.

Double It Or Cut It By Half

Good games can rarely be created in a vacuum, which is why many designers advocate an iterative design process, during which a simple prototype of the game is built very early and then iterated on repeatedly until the game becomes a shippable product.

Sid called this process "finding the fun," and the probability of success is often directly related to the number of times a team can turn the crank on the loop of developing an idea, play-testing the results, and then adjusting based on feedback.

As the number of times a team can go through this cycle is finite, developers should not waste time with small changes. Instead, when making gameplay adjustments, developers should aim for significant changes that will provoke a tangible response.

If a unit seems too weak, don’t lower its cost by 5%; instead, double its strength. If players feel overwhelmed by too many upgrades, try removing half of them. In the original Civilization, the gameplay kept slowing down to a painful crawl, which Sid solved by shrinking the map in half. The point is not that the new values are likely to be correct - the goal is to stake out more design territory with each successive iteration.

Imagine the design space of a new game to be an undiscovered world. The designers may have a vague notion of what exists beyond the horizon, but without experimentation and testing, these assumptions remain purely theoretically. Thus, each radical change opens up a new piece of land for the team to consider before settling down for the final product.

One Good Game Is Better Than Two Great Ones

Sid liked to call this one the "Covert Action Rule," a reference to a not-altogether-successful spy game he made in the early ’90s:

The mistake I made was actually having two games competing with each other. There was an action game where you break into a building and do all sorts of picking up clues and things like that, and then there was the story which involved a plot where you had to figure out who the mastermind was and what cities they were in, and it was an involved mystery-type plot.

Individually, each part could have been a good game. Together, they fought with each other. You would have this mystery that you were trying to solve, then you would be facing this action sequence, and you’d do this cool action thing, and you’d get out of the building, and you’d say, "What was the mystery I was trying to solve?" Covert Action integrated a story and action poorly because the action was actually too intense - you’d spend ten minutes or so of real time in a mission, and by the time you got out, you had no idea of what was going on in the world.

In other words, even though both sections of the game were fun on their own, their co-existence ruined the experience because the player could not focus her attention on one or the other.

This rule points to a larger issue, which is that all design choices only have value in relation to one another, each coming with their own set of cost/benefit trade-offs. Choosing to make a strategic game also means choosing not to make a tactical one. Thus, an idea may be “fun” on its own but still not make the game better if it distracts the player from the target experience. Indeed, this rule is clearly the reason why the Civ franchise has never dabbled with in-depth, tactical battles every time combat occurs.

However, sometimes multiple games can co-exist in harmony with each other. Sid’s own Pirates! is an example of a successful game built out of a collection of fighting, sailing, and dancing mini-games. However, these experiences were always very short - a few minutes at the most - leaving the primary focus on the meta-game of role-playing a pirate. Each short challenge was a tiny step along a more important larger path, of plundering all Spanish cities or rescuing your long-lost relatives.

Another example of a successful mix of separate sub-games is X-Com, which combined a tactical, turn-based, squad-level combat game with a strategic, real-time, resource-management game. As with Pirates!, what makes X-Com work is that the game chose a focus - in this case, the compelling tactical battles between your marines and the invading aliens.

The high-level, strategic meta-game exists only to provide a loose framework in which these battles - which could take as long as a half hour each - actually matter. One doesn’t fight the aliens to get to manage resources later; instead, one manages resources to get to perform better - and have more fun - in future battles.

Do Your Research After The Game Is Done

Many of the most successful games of all time - SimCity, Grand Theft Auto, Civilization, Rollercoaster Tycoon, The Sims - have real-world themes, which broadens their potential audience by building the gameplay around concepts familiar to everyone.

However, creating a game about a real topic can lead to a natural but dangerous tendency to cram the product full of bits of trivia and obscure knowledge to show off the amount of research the designer has done. This tendency spoils the very reason why real-world themes are so valuable - that players come to the game with all the knowledge they already need.

Everybody knows that gunpowder is good for a strong military, that police stations reduce crime, and that carjacking is very illegal. As Sid puts it, "the player shouldn’t have to read the same books the designer has read in order to be able to play."

Games still have great potential to educate, just not in the ways that many educators expect. While designers should still be careful not to include anything factually incorrect, the value of an interactive experience is the interplay of simple concepts, not the inclusion of numerous facts and figures.

Many remember that the world’s earliest civilizations sprang up along river valleys -- the Nile, the Tigris/Euphrates, the Indus -- but nothing gets that concept across as effectively as a few simple rules in Civilization governing which tiles produce the most food during the early stages of agriculture. Furthermore, once the core work is done, research can be a very valuable way to flesh out a game’s depth, perhaps with historical scenarios, flavor text, or graphical details. Just remember that learning a new game is an intimidating experience, so don’t throw away the advantages of an approachable topic by expecting the player to already know all the details when the game starts.

The Player Should Have The Fun, Not The Designer Or The Computer

Creating story-based games can be an intoxicating experience for designers, many of whom go overboard with turgid back stories full of proper nouns, rarely-used consonants, and apostrophes. Furthermore, games based on complex, detailed simulations can be especially opaque if the mysterious inner workings of the algorithmic model remain hidden from view. As Sid liked to say, with these games, either the designer or the computer was the one having the fun, not the player.

For example, during the development of Civilization 4, we experimented with government types that gave significant productivity bonuses but also took away the player’s ability to pick which technologies were researched, what buildings were constructed, and which units were trained, relying instead on a hidden, internal model to simulate what the county’s people would choose on their own.

The algorithms were, of course, very fun to construct and interesting to discuss outside of the game. The players, however, felt left behind -- the computer was having all the fun -- so we cut the feature.

Further, games require not just meaningful choices but also meaningful communication to feel right. Giving players decisions that have consequence but which they cannot understand is no fun. Role-playing games commonly fail at making this connection, such as when players are required to choose classes or skills when "rolling" a character before experiencing even a few seconds of genuine gameplay.

How are players supposed to decide between being a Barbarian, a Fighter, or a Paladin before understanding how combat actually works and how each attribute performs in practice? Choice is only interesting when it is both impactful and informed.

Thus, in Sid’s words, the player must "always be the star." As designers, we need to be the player’s greatest advocate during a game’s development, always considering carefully how design decisions affect both the player’s agency in the world and his understanding of the underlying mechanics.