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.
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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