GD Column 17: Water Finds a Crack

The following was published in the March 2011 issue of Game Developer magazine…

“This is what games are for. They teach us things so that we can minimize risk and know what choices to make. Phrased another way, the destiny of games is to become boring, not to be fun. Those of us who want games to be fun are fighting a losing battle against the human brain because fun is a process and routine is its destination.”

– Raph Koster, A Theory of Fun

Many players cannot help approaching a game as an optimization puzzle. What gives the most reward for the least risk? What strategy provides the highest chance – or even a guaranteed chance – of success? Given the opportunity, players will optimize the fun out of a game.

Games, however, are so complex that it is difficult to anticipate exactly how players will optimize a game until after release, once thousands bang away at the game and share their ideas with each other online. Often, designers don’t even understand their own games until they finally see them in the wild.

A phrase we used on the Civilization development team to describe this phenomenon is that “water finds a crack” – meaning that any hole a player can possibly find in the game’s design will be inevitably abused over and over. The greatest danger is that once a player discovers such an exploit, she will never be able to play the game again without using it – the knowledge cannot be ignored or forgotten, even if the player wishes otherwise.

Civilization 3 provides a simple example with “lumberjacking” – the practice of farming forests for infinite production. Chopping down a forest gives 10 hammers to the nearest city. However, forests can also be replanted once the appropriate tech is discovered.

This set of rules encourages players to have a worker planting a forest and chopping it down on every tile within their empire in order to create an endless supply of hammers. However, the process itself is tedious and mind-numbing, killing the fun for players who wanted to play optimally.

Tank-Mages and Infinite City Sleaze

One of the dangers of players looking to optimize a game is that a single dominant strategy will emerge that drowns out all others. In the MMO world, the shorthand term for this predicament is the “tank-mage” – a reference to Ultima Online, in which certain hybrid class builds could both wear heavy armor and cast powerful damage spells.

Thus, the character served as both the damage absorber (the “tank”) and the damage dealer (the “mage”), displacing most other possible character builds. Almost every MMO has experienced some version of the tank-mage as players try to find the optimal build for all situations.

The Civ series has its own version of the tank-mage – the strategy of spamming settlers for “infinite city sleaze” (or ICS), a bane of the franchise from the beginning. The essential problem is that 50 size-2 cities are more powerful than 5 size-20 cities as a number of bonuses are given out on a per-city basis. For example, every city gets to work its home tile for free, which means that a size-2 city works 3 tiles with only 2 citizens (1.5 tiles per citizen) while a size-20 city works 21 tiles (only 1.05 tiles per citizen).

The problem is that while ICS makes beating the highest difficulty levels trivially easy, handling 100 cities is a management nightmare. Players who pursued this strategy – or even less extreme versions of it – were always aware that they were breaking the game but often simply couldn’t stop themselves.

Armed with knowledge from the earlier versions of the game, we were able to counter ICS ahead of time with Civ 4 by adding a per-city maintenance cost that scaled with the total number of cities. Thus, building too many cities too early crippled a player’s economy, killing ICS at long last.

The reason to kill tank-mages and ICS is that a single, dominant strategy actually takes away choice from a game because all other options are provably sub-optimal. The sweet spot for game design is when a specific decision is right in some circumstances but not in others, with a wide grey area between the two extremes. Games lose their dynamic quality once a strategy emerges that dominates under all conditions.

Undervaluing Time

When presenting players with a choice, games typically pairs a specific reward with a certain level of risk. When gamers discover that one play style offers a trickle of reward for little or no risk, they will inevitably gravitate towards that degenerate strategy.

In other words, players will trade time for safety, but they risk undervaluing their own time to the point that they are undermining their own enjoyment of the game. A classic example is the skill system from Morrowind, which rewards players for repeating any activity. Running into a wall for hours increases the Athletics skill while jumping over and over again increases the Acrobatics skill. Many players couldn’t stop themselves from spending hours doing mindless activities for these cheap rewards.

Another example of players undervaluing their own time comes from growth, production, and research overflow in the Civ series. Every turn, cities produce food, hammers, and beakers, filling up various boxes. Once these boxes are full, new citizens, buildings, units, and technologies are created.

For example, if a civilization produces 20 beakers per turn, and Writing costs 100 beakers, the technology will be discovered after 5 turns. However, if the same civilization produces 21 beakers per turn, the box for Writing will contain 105 beakers at the end of 5 turns. In that situation, after Writing is discovered, the extra 5 beakers are thrown away so that the box will be empty when the player starts researching Alphabet on the next turn. Players quickly realized that when they came close to finishing a tech, they could adjust their tax rate so that no beakers would be wasted (because those beakers are all potential gold at a different rate).

A similar dynamic exists with food and hammers for city growth and production. Thus, the game’s rules encourage players to visit every city every turn to rearrange their citizens to ensure no food or hammers will be lost. This micro-management is actually a somewhat interesting sub-game, but clearly not how the designers want the players to be spending their time as it completely bogs down the game. (We solved this in Civ 4 by simply applying the overflow food/hammers/beakers to the next citizen/unit/building/technology.)

Players who adopt this strategy often refer to the game as being heavy on “micro-management” because they can no longer resist playing the game without squeezing every last drop out of their cities. The problem is even worse in multi-player as gamers who don’t micro-manage their cities will always fall behind in the race for more growth and production.

The designers don’t want people to play this way; nonetheless, the rules inadvertently encourage it. Again, designers often don’t understand their own games as well as the players do. The problem with a gamer undervaluing his own time is that, while the easy rewards may feel good at first, eventually the amount of time required will slowly seep away the fun per minute, until the game begins to feel like a grind.

Good Exploits?

However, designers can go too far by trying to remove all exploits from a game. Often, the right choice depends upon the game’s context. Does the exploit drown out all other play styles, or is it a fun, alternative way to play? Does the degenerate strategy create an endless grind, or is it a quick shortcut for players who need a little help?

The famous, endless free lives trick from Super Mario Bros. – in which the player bounced a turtle shell repeatedly against a block staircase for long strings of 1UP’s – was actually not a bug but a feature the team included on purpose. In exchange for mastering a small dexterity challenge, players can quickly mine all the free lives they need to progress in the game. Discovering and abusing a hole in a game’s design can be a fun experience – giving the player a unique sense of mastery – as long as the exploit doesn’t ruin the game for the player (or the player’s opponents).

If possible, designers should provide the ability to turn an exploit on or off, giving the players control over their worst instincts. For example, most games with save/load functionality can be abused by players to improve their odds; an RPG in which smashing a box produces random loot can be reloaded as many times as necessary until the best possible weapon or armor appears.

With Civ 3, we introduced a feature that preserved the game’s random seed in the save game file, guaranteeing that individual combats would play out the same way regardless of how many times the player reloaded the game. No longer were players tempted to reload every bad combat result, which could slow the game to a crawl.

However, the community response was not what we anticipated. Although some players appreciated that they were no longer tempted to reload combats, many others were frustrated that one of their old tricks disappeared. Indeed, some angry fans actually felt that the game was cheating on them by always reproducing the same combat result!

We solved this problem by turning this feature into an option on game start. Players who want the chance to reload a particularly unlucky roll can use the old exploit, but the game, by default, discourages this work-intensive strategy. Ultimately, the designer can’t go wrong putting the player in control of his or her own experience.

12 thoughts on “GD Column 17: Water Finds a Crack

  1. The otherwise awesome Alpha Centauri was a somewhat ruined for me by the discovery that you could use a special ability of the Gaians to starve the other races. Specifically you could use the fact that the Gaian flying units could stay airborne forever to efficiently destroy farms, forests, mines etc. around a city and starve it of resources. Arguably it was a legitimate expression of the power of an dominant airforce but it basically meant I couldn’t play that race. As you say, you can’t unring a bell.

  2. “Ultimately, the designer can’t go wrong putting the player in control of his or her own experience.”

    This kind of player empowerment does come at a cost: asking players to make decisions they don’t necessarily understand, and embiggening the initial interface. It might be negligible for people who post on CivFanatics, or have spent $50 and gained certain expectations. But not all such costs are so small, and not all audiences are as committed to the game.

  3. @Jared Garst

    I completely agree that we shouldn’t be asking players to make decisions they don’t understand, which is why this option was hidden in the Advanced Setup screen.

  4. On the topic of ‘bad’ knowledge, I had used the ICS strategy in Alpha Centuri specifically to avoid micro-managing. Establishing 4 or 5 great cities and then a low-efficiency research/income ‘farm’ on the rest of the map generally let me focus on my core while willfully neglecting the other 200+ colonies.

    I hardly ever used the ICS strategy in Civ 3, but I’m curious to see how the game balance changes now…

    Completely off topic, but why I initially visited your site; The AI in Civ 3 is amazing, and is the only game I still play as an adult. Your coding literally was one of the defining components of my friends and my adolescence.

  5. I wonder about that last line in the post.
    Can not something be lost in the experience if the designer hands over power to the player? Of course it’s a matter of what and how much is given to the player, but in pronciple, I think this question merits an extended look.

    I suppose that as a piece of entertainment, a game should allow the player/consumer have his way with it, but looking at a game as a piece of art to be experienced, one may lose authorial intent when doing so, no?

  6. I really like this article. I do particularly like games that give me more control over them, especially modding. However, there are limits to what can be allowed in multiplayer games because it is likely that different players will wish for different experiences at different times. I’d also point out that, in multiplayer games, there is a meta-gaming effect (i.e. the effect on gameplay of community choices based on the perception of the quality of a strategic or tactical choice) that is probably nearly impossible to predict pre-launch/pre-patch from the developer standpoint.

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