Sunday 26 June 2011

The Panda's Hit Points

I guess everyone who writes about D&D has to tackle the enigma of hit points sometime. Here's the basic paradox:

1. Hit points are a gross abstraction, representing nothing more specific than how long a being can stay in combat without dying. By most accounts, a fighter with 50 hit points taking damage is dodging, ducking, wearing down her favor with the Gods, running out of luck. A dinosaur with 50 hit points taking damage, though, is taking huge slashes to its flesh and hide. This is poison to those who want their game to be a sensible simulation. It's one of the most frequent "problems" that tinkerers try to fix in D&D - by separating body points from luck points (Star Wars d20, etc. etc.), physical damage from defensive skill (Runequest, etc., etc.).By the standards of simulation, hit points are terrible.

2. Hit points are the most successful game element to be exported from D&D. Almost without exception, any computer or board game that simulates a fight at the skirmish level for the past 35 years has used hit points, life points, health bar, or some variation thereof, instead of a more realistic system where individual injuries are tracked. Compare the longevity and sales of Soul Calibur vs. Bushido Blade. By the standards of meeting gamers' needs, hit points are great.

I'm going to take a roundabout trip to explain the discrepancy between the two. I want to argue that hit points are an evolutionary exaptation in game design, adapting to needs gamers have that a more realistic system would not meet.

Exaptation in evolutionary biology means the development, through natural selection, of a new function for a given structure. The concept was popularized by Stephen Jay Gould in an essay on the panda's thumb. This appendage, used to grasp bamboo, actually evolved from one of the panda's wristbones. Another example is feathers, which originally evolved on dinosaurs for temperature regulation but then became important in flying.

Games also have selection pressure. In the game designer's ideal world, the best-selling games will be those that use elegant mechanisms to capture the essential experience of that which the designer is simulating. In the real world, market-dominating games tend to be meatballs like AD&D in its heyday and Monopoly.

Faced with this tragic state of affairs, designers will often resort to a narrative in which, Microsoft-like,  industry leaders achieved their position through sheer corporate throw-weight and user conservatism. I am not discounting these factors. But I want to present an alternative view. Although these games are anathema to intelligent design, they often hold within them features exapted from other games that crudely address some of the very real needs of game players. The crudity of these panda thumbs may offend the sensibilities of refined gamers, but they help explain how these games come out ahead in the more rough-and-tumble process of mass market natural selection.

Take Monopoly as a simulation of real estate dealing, for example. In real life, real estate moguls do not randomly move house from street to street, hoping they will not be forced to pay rent in an an expensive location. Their purchases do not depend on their physical residence, either, and precious few of them enter beauty contests. What a lousy simulation, huh?

These features make more sense in accounting for Monopoly's longevity as a family game. They are exaptations from dice-and-track games (Parcheesi, Snakes and Ladders) that let young kids play along and even succeed sometimes by sheer chance. Monopoly also gathers a couple of other game concepts alien to the simulation of real estate dealing - set trading and collecting, chance cards.

So where are hit points exapted from? Some of you may already know, but here's a roundabout clue:

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More next time.


  1. Interesting article. With a title like that I certainly had to read what you were talking about. Comparing game design to evolution certainly fits. Like the moths who adapt their coats after a fire game designers certainly tend to cling to what works for their niche market.

    I had never considered Battleship to be a game which had hit points, though next time I play I can't help but believe I'll envision every ship with a heart bar straight out of The Legend of Zelda.

  2. Let's just hope Exaptation doesn't become the next gamer buzzword, the way Bricolage did on The Forge (after someone used that term to explain the same process...)

  3. @Talysman: Aha, thanks for that, there are certainly some similarities. Assuming this thread is representative of the dialogue about bricolage, a main difference I see is that the Forge crowd uses it to describe the process of using and improvising rules and rulings in any given gaming group. My evolution analogy, perhaps, is on a wider scale, covering the market selection of game rules. I also want to show that there is a functional point to the rule being exapted; that elegance is not the only yardstick of function in a game, except to the rare bird who cannot have fun unless the game is designed with elegance.

  4. So what's the alternative? A more "realistic" hit location chart? Arm, leg, head, torso, etc? If you characters make it to level 5ish, say, they will all have wooden leg, a hook, and be missing an eye! I like the mechanic that uses hit points to get you down to zero, then use Constitution or some other stat to go the rest of the way. It's an imperfect abstraction, but it's just a game, and as such, it works well enough, IMHO.

  5. Nice. And, there are certainly selective pressures acting on the rules-- memory and time constraints will be pushing against complexity, while immersion and involvement will push for more options and intricacy.

    Do you think there are other examples? Level seems to be used the way other games before it were used and Class seems to have evolved through play. Maybe the 3d6 attribute roll? Where did that come from?

  6. @TC: Level and Classes probably also derive directly from Chainmail's heroes, superheroes and so on. I really can't say about the 3d6 though; that is most likely original to D&D.

  7. Arm, leg, head, torso, etc? If you characters make it to level 5ish, say, they will all have wooden leg, a hook, and be missing an eye!

    Congratulations, you are playing Warhammer Fantasy Roleplay!