Hello! Not much news to report since last week, so I’ll jump straight into another Design Rules discussion. This is a design rule I formulated years ago, and express like this:

When you create a system with perverse incentives, don’t be surprised when players act perversely.

Now, I’m not saying players are perverts. I’m using perverse in its dictionary definition: showing a deliberate and obstinate desire to behave in a way that is unreasonable or unacceptable [to the game designer], often in spite of the consequences. You’ll note that I added [to the game designer] to clarify who exactly finds the behavior unacceptable, because society at large probably doesn’t care if you’re abusing some loophole the game designer left open.

To put it another way: If players find an advantage in playing your game the “wrong” way, that’s what they’ll do. And it’s your fault, not theirs. Let’s take a look at a couple of examples.

Axis & Allies: The Infantry Turtle

I love Axis & Allies; it lets me play something that feels like a wargame in an afternoon and generally feels faithful to the genre. However, A&A has a strong perverse incentive baked into the most common unit in the game: the infantry piece has an attack value of 1, and a defense value of 2.

Now, on its face that seems pretty reasonable. Anyone who’s read even a little military history knows that infantry forces are good for holding ground, and attacks generally fail unless attackers outnumber defenders (assuming similar technology). This rule provides good “simulation value” since it makes infantry behave like we’d expect them to in real life.

But here’s the perverse incentive: It means the only smart way to play Axis & Allies is to pour your money into buying as much infantry as you can, and stand on the defensive. If your opponent does this and you don’t, you’ll lose 90% of the time. Years and years ago, a smart player by the name of Don Rae christened this “the infantry push mechanic” and wrote several illuminating essays about it. (Worth looking up, if you’re a serious Axis & Allies fan.)

As a result, games between good players generally result in giant stacks of infantry that refuse to attack each other. Maybe that’s optimal play, but it’s not fun play. Axis & Allies is supposed to be a game where people feel good about buying tanks or bombers or submarines and are rewarded for taking the offensive. The effectiveness of the “turtling up” strategy acts as a perverse incentive, making competitive players play a long, boring game.

3^rd Edition Dungeons & Dragons: The Spirit Master

Never heard of the Spirit Master character class for D&D? That’s because it was cut from the Player’s Handbook during playtesting. Basically, the Spirit Master was an arcane spellcaster designed on the mechanics of the sha’ir spellcaster from the 2^nd Edition Al-Qadim D&D setting. The Spirit Master’s special trick was that when he prepared spells for the day, he could attempt to choose a spell of a higher level than he could normally select if he succeeded on a die roll. Walking into a dungeon as a 1^st-level caster with an invisibility or web spell up your sleeve was fun and exciting.

Until Jonathan Tweet demonstrated why it was a bad idea in one of our internal playtests.

Jonathan brought a Spirit Master to the game, and tried for the best spell he could possibly get. Naturally, he didn’t roll high enough. So he shrugged and said, “Okay, I don’t leave the inn until I succeed on that roll. So a couple of weeks go by, and sooner or later the day comes that I’m ready to adventure, right?”

Well, that wasn’t what we wanted people to do with the Spirit Master. But it was clearly the smart way to play. Jonathan wasn’t being a perverse person—he was demonstrating what would happen if we included the perverse incentive of “wait until you get your best spell” in the game. That pretty much killed the Spirit Master class.

Avoiding Perverse Incentives

Ultimately, people don’t play the game you think you designed. They play the game they find when they open the box and read the rules. As a designer, you have a huge internal bias toward trying to make the game you think you’re making run as cleanly as possible. It’s really hard to look at your own game and try to play it “the wrong way.”

That means the best way to spot perverse incentives is to make sure people who don’t have your assumptions test your game. You’re in for playtesting, lots of it, and preferably with folks who don’t already have a stake in the game’s development. (It’s worth noting that perverse play can often help you find the game you should be making. If people have a lot of fun playing the game the “wrong” way, maybe you shouldn’t fight it.)

Sometimes you can get rid of a perverse incentive with an easy change to the rules. But sometimes you can’t. When that happens, you either embrace the way the game is actually being played, or you throw it out and try again. Axis & Allies lives with its perverse incentive—it has the advantage of favoring more skillful players who can find ways to entice opponents into making risky attacks. But over the various editions of the game, A&A has also re-costed or powered up units that aren’t infantry to entice players to try other strategies.

Finally, perverse play might point out ways to reward alternate strategies, or perhaps take the sting out of falling behind. The Brotherwise Games board game Unearth has an elegant mechanic that pays players who invested in trying to claim a card but fell short—you can use that currency to pursue an alternate victory strategy by building monuments. In fact, it can sometimes be better to not win the card you’re committing to.

Which sounds perverse. Until it isn’t.