Localized Damage Systems

tim-cain system-design hit-points localized-damage armor status-effects rpg-design game-complexity fallout outer-worlds

Abstract

Problem: Should RPGs use localized damage (separate health pools or status effects per body part) instead of a single hit point bar, and what are the trade-offs?

Approach: Tim Cain walks through the design space starting from basic hit points, then layering on localized health pools, location-based armor, status effects, aimed shots, and perks — examining the cascading complexity each layer introduces.

Findings: Localized damage opens up rich design possibilities (aimed shots, location-specific armor, stealth boots, perception-reducing helmets, ameliorating perks) but dramatically increases system complexity for programmers, UI designers, and players. A viable middle ground is keeping one global health pool while applying location-based status effects and armor separately.

Key insight: Every layer of mechanical complexity bifurcates your audience — some players are drawn to depth, others leave because they don't want to learn a new system. The designer must weigh richness against accessibility.

Source: https://www.youtube.com/watch?v=H_Ddhxf7ASk

Hit Points as the Universal Baseline

Tim begins by establishing why hit points have endured for 50–60 years: they are an abstraction of generalized damage that is trivially easy to understand and implement. They're so standardized that games don't even explain what they are — the same way no game explains what a sword is. Everyone already knows.

Even this simple system gets complicated when you layer on secondary systems like exhaustion, poison, or radiation. Each needs either its own bar or some interaction with the health bar. Questions immediately arise: if I heal while irradiated, does the radiation shrink? If I level up while poisoned, does my new max health push the poison boundary? These all need designer decisions and clear player communication.

What Localized Damage Actually Means

Localized damage goes far beyond aimed shots and crippling. Tim breaks it into several layers that cascade in complexity:

Localized Health Pools

Each body part (head, torso, arms, legs) gets its own hit point pool. Damage is applied to the specific location that was hit. This immediately raises questions about aimed shots — even without player aiming, the system must decide where each attack lands.

Tim references his own work: The Outer Worlds used real-time aiming, while Fallout used called shots where players selected a target location.

Location-Based Status Effects

When a body part takes enough damage, effects kick in:

  • Main arm crippled — reduced weapon skills, lockpicking penalties
  • Off-hand crippled — shield skill and two-handed weapon penalties
  • Leg crippled — reduced movement, lower jump height, reduced carry capacity

These effects don't require separate health pools — they can be applied as status effects while damage still draws from a single global pool.

Location-Based Armor

Instead of monolithic "I'm wearing plate," players equip helmets, greaves, arm guards, and chain mail shirts separately. This opens up non-combat effects:

  • Soft-soled boots: less damage reduction, but stealthier movement
  • Heavy helmets with eye slits: high protection, but reduced perception
  • Noisy armor: better defense, but enemies hear you coming

Ameliorating Perks

Once negative effects exist, perks can reduce them. A perk might let you wear noisy armor more quietly, or reduce the perception penalty from restrictive helmets. The more effects you have, the larger your perk design space becomes.

The Complexity Cascade

Tim emphasizes that this system isn't harder for a designer to conceive — it's harder for programmers to build and for players to understand. The complexity compounds through unanswered questions the designer must resolve:

  • AoE attacks: Does a fireball damage all armor equally? Is it split proportionally (50% torso, 10% per limb)?
  • Unaimed attacks: Do they default to torso, or hit randomly with weighted percentages?
  • Non-humanoid enemies: How do you aim at a dragon (four legs, two wings)? What about an ooze with no body parts at all?
  • Healing: Do potions heal all pools equally? Which status effects clear first? Which require special removal?
  • Poison and radiation: With multiple pools, does radiation spread across the whole body? Does poison stay local to the hit location?
  • Quadrupeds vs. bipeds: Is crippling one leg of a four-legged wolf as debilitating as crippling one leg of a human?
  • Ghosts and immunities: Can you cripple a ghost? Some enemies may be immune to damage effects just as others are immune to damage types.

The One-Pool Compromise

Tim suggests a practical middle ground: keep a single monolithic health pool for all damage, but still have location-based armor, aimed shots, and status effects. Damage draws from one number, but where you're hit determines which status effects apply and which armor piece absorbs the blow. This preserves most of the design richness while dramatically simplifying the underlying system.

Innovation and Audience Bifurcation

Tim offers a broader design philosophy observation: every design decision bifurcates the gaming audience. Turn-based vs. real-time, isometric vs. first-person — each choice causes some players to walk away. Making a simple system more complicated is the same kind of split. You may gain players who crave depth, but you will lose players who don't want to learn something unfamiliar.

This, Tim notes, is one reason (beyond corporate risk aversion) that games innovate less than they could. Innovation is genuinely risky because unfamiliar systems drive away a portion of the audience who simply say, "I don't get it. I don't feel like learning it."

References