A few weeks ago, I described my system for rating game quality. My "five axes" had two important qualities. First, the descriptors are orthogonal, which is a fancy mathematics word for "independent". A game with a given strategic complexity has equal chances of being aesthetically beautiful as aesthetically bland, and aesthetic quality doesn't correlate at all with strategic quality. Second, all the descriptors are "per se" good things; all other things being equal, a game with greater strategic depth is better than one with shallower strategy.
Of course, no system can capture each and every trait that makes a game good or bad. Two that Alex and I discussed after I published the article are approachability, which Alex and I posted slightly different takes on last week, and complexity, which is the subject of this post. We'll define complexity as the number of things "going on" in a game: the sum of all the rules, mechanics, decisions, design, and implementation.
Complexity works a little differently than the traits I use as my five axes in that it's not orthogonal to the other axes, and it's not per se desirable for determining quality. Complexity is in fact highly correlated to strategic depth (strategically deeper games tend to be more complex) and adaptability (more complex games often have more variety for ways to play), in addition to approachability (more complex games can be less approachable simply because there's more happening).
Further, a more complex game is not necessarily a better game. Sometimes, more complexity makes a game better. For example, tic-tac-toe and Connect Four are nearly identical in aesthetics, mechanics, and general feel, but Connect Four is a better game because it's strategically deeper, and most of that strategic depth comes from its increased complexity.
On the other hand, sometimes more complexity makes a game worse because it makes a game more difficult to play but doesn't improve its strategic experience. I came down pretty hard on Ascension: Rise of Vigil because it takes a good game (Ascension) and adds a mechanic that makes things more difficult to keep track of while simultaneously increasing the game's variance.
And often, a greater-complexity game is neither markedly better or worse, it's just more complicated. For any given play style, there's probably a complexity optimum that's sometimes undershot, sometimes overshot, but often on a complexity plateau where all you're doing by adding more complexity is adding more complexity. In that case, the simplest version of the game that provides the same quality is the best.
A situation that lends itself well to examining where the complexity optimum lies is in games with lots of expansions. Maybe you've noticed this yourself: in your favorite thirty-seven expansion game, you really like playing with a handful of them, there's a few you never want to see opened again, and most of them you could take or leave, right? I'll illustrate the phenomenon with my own favorite thirty-seven expansion game, Dominion.
Rules exceptions, conditionals, and single game-altering mechanics promote "bad" complexity. Probably the only Dominion iteration that comes close to "bad" complexity is Alchemy, which relied on entirely different ways of thinking than any of the rest of Dominion. Cards costing multiple types of resources, situations where you can control elements of your opponents' turns, and cards that force you to make dozens of different decisions per turn all turn Alchemy into a high-complexity game without necessarily making it more fun or strategically deeper.
Having said all that about shades of complexity and a hypothetical quality vs. complexity curve, Alex brings up an important point: people tend toward games that are as complex as they like them to be. To a non-board gamer, maybe Dominion in any capacity is too complex. To a chess player or war-gamer, maybe Dominion in any capacity is too simple and too inclined toward variance.
How does that affect a game's quality score? On one level, it subconsciously inclines players away from games that might deserve a higher rating. I rate high-concept warfare games like Diplomacy fairly low in general, ostensibly because I find they take too long and don't feature intriguing mechanics, but really because I find it difficult to wrap my head around every single player's tree of strategic possibilities. In other words, it's too complex for my tastes.
On the other hand, given that I know high-concept warfare games aren't my thing, I tend not to seek them out. Therefore, I'm prevented from polluting their ratings pools with what would be artificially low scores to legitimate fans of the genre. Both are effects designers should be aware of. And although complexity isn't an attribute that's easy to score directly, it has an effect, subtle or overt, on practically every measure of quality.
In conclusion, here are some important considerations on complexity for a game designer: does a mechanic enhance the strategic depth of the game or is it merely clever? Is every decision the player is required to make both interesting and meaningful? Have I made my game so complex that it's no longer approachable? Does changing the number of players substantially alter the rules and the game's ease of implementation?