Game Design Specification Sections

The Three Pillars (Plus UX)

Tim frames the design spec around a progression he's advocated before: Setting first, then Story, then System Mechanics. User Experience (UI/UX) is treated as a fourth major area that runs parallel to the mechanics.

The caveat up front: the answer depends entirely on the game. A puzzle game won't need a combat section. Tim uses a fantasy RPG as his example to give the most comprehensive answer possible.

Setting

The setting section describes the world the game takes place in:

• The world itself and its history
• Which areas of the world the game will actually cover (you may have a big world but only use a portion)
• Detailed history of the game's specific region
• The peoples, animals, and monsters that inhabit it

This lays the groundwork for everything else. It's referenced later when you detail specific areas.

Story

The story section covers:

• Main acts — the major story beats the player progresses through. Fallout had only three acts (find the water chip, stop the mutants, stop the Master). Arcanum had 27. Tim believes the right number lies somewhere between those two extremes.
• Key characters — the NPCs that drive the story forward and deliver main quests. In games where characters can be killed, you must plan for how the story progresses if the player murders them — whether a secondary NPC steps up, you find their journal, or some item on their body leads to the next quest stage.

System Mechanics

This is the largest section by far, with numerous subsections each requiring deep detail.

Character System

• Attributes, skills, spells, perks, traits, backgrounds, races, flaws — not every game has all of these, but most RPGs have a good chunk
• For each subsection: what they are, how they're obtained, how they're raised during play, what the ranges are, what happens at level-up, whether they can be respecced

Character Creation

• Separate from the character system (mechanics vs. UI, as with inventory)
• What gets selected at creation — point-buy vs. dice rolls
• The mechanical rules for the creation process

Leveling Up

• Exactly what happens every time the player gains a level

Status Effects

• Poison, slowed, frozen, electrified, prone, knocked down, knocked out, and potentially dozens more
• Tim has worked on games with over 100 status effects
• Each needs: what applied it, how long it lasts, how it interacts with other status effects
• Sources: perks, skills, backgrounds, spells, equipped items, combat, environmental hazards
• This section grows as you design other systems (new magical items and creatures keep adding effects)

Inventory

• How encumbrance works
• Equipment slots (helm, face, torso, arms, legs, hands, feet, etc.) for both player and NPCs

Combat

A massive section with tons of subsections:

• Combat mode — real-time, real-time with pause, or turn-based
• Skill usage in combat — how skills interact with combat actions
• Hit/miss rules — hitting, missing, critical hits, critical misses
• Weapons — melee vs. ranged, projectile vs. hitscan
• Armor — what slots they occupy, what protection they provide
• Magical versions — of both weapons and armor (these feed back into the status effects section)
• Creatures — animals, monsters, NPCs; their abilities and attacks (which may add even more status effects)

Dialogue

• How dialogue branching works
• Restrictions — e.g., Tim's games limited dialogue nodes to no more than five response lines displayed simultaneously; if conditions made more possible, you had to ensure no more than five could be true at once
• How skills work in dialogue
• How dialogue affects NPC reaction and vice versa

Stealth

• How hiding works — interaction with lighting and cover
• How NPCs detect the player
• Locks — difficulty levels, interaction with skills and perks
• Stealth paths for quests — tunnels, vents, computer hacking, picking cabinets
• NPC reactions to catching the player

Companions

• Where and when each companion is acquired in the story
• How many exist in the game; how many you can have simultaneously
• Whether the limit depends on an attribute, perk, or skill
• Whether companions can decide to leave
• Bonuses and penalties — some give combat bonuses, others impose restrictions ("you're not allowed to kill good people when this companion is around")
• Companion reactions to the main storyline
• Companion personal quests — their own storylines and problems they want the player's help resolving

Economy

• Loot and loot tables — distribution among NPCs and encounters
• Vendors — how they get and refresh their inventory
• Crafting — materials, recipes, and its effect on the overall economy

Areas

• Detailed descriptions of every game area: cities, towns, dungeons, castles
• How big they are
• Which NPCs are present
• Preset encounters (always there) vs. random encounters (in dungeons, wilderness, etc.)

User Experience

Broken into three subsections:

Pre-Game

Everything the player sees before actually playing:

• Main menu (new game, load game, options, credits, quit)
• Options: visual settings, audio settings, accessibility, combat options
• Some options set here are defaults for all games

Out-of-Game (Pause Menus)

Menus accessed while playing but not part of the game world:

• Pause, save game, options
• Important distinction: some options apply globally to all saves, others apply only to the current game (e.g., changing difficulty mid-game vs. setting a default)

In-Game

All the gameplay UI:

• HUD
• Character screen and level-up screen
• Inventory screen
• Quest journal (quests, rumors, notes)
• Dialogue UI
• Looting, bartering, pickpocketing interfaces
• Local maps and world maps
• Sleep/wait UI
• Message system (damage notifications, status changes like "you are now on fire")

Cross-Cutting Considerations

Tim identifies three considerations that affect multiple sections:

PC vs. NPC Asymmetry

Rules that work identically for players and NPCs are the exception. Example: a high melee skill might let you knock out opponents — fun for the player to do to NPCs, but terrible when done to the player. So you'd specify "knockout cannot be applied to the player character." Similarly, NPCs might fly (bats, dragons) but if you let players fly, they'll immediately try to fly into buildings.

Multiplayer

If the game supports multiplayer, some features may need to disappear or change. Turn-based combat might not work in multiplayer. Character creation might be replaced by taking over companions in someone else's campaign. These differences need to be spelled out.

Design Fallbacks

A section Tim has added to his more recent specs — simpler alternative designs that can replace complex ones if you run out of time or they don't work. The Outer Worlds example: Tim wanted throwing grenades, but the arcs couldn't be made to work properly. The fallback was a grenade launcher weapon. Removing grenades had cascading effects — it eliminated the throwing skill, which rolled unarmed into melee. "You often can't delete something from the game and have no effect on anything else."

The Arcanum Design Spec

Tim shows the printed Arcanum design specification: 48 pages, written when the game was still code-named "Epic" (confusingly, the same codename used for their planned post-apocalyptic fourth game). Key observations:

• Written before any publisher was interested in the game
• Surprisingly close to what shipped
• Contains a world map very similar to the final cloth map
• Still incomplete — UI sections listed as "TBD," loot tables marked "TBD"
• Used to secure the contract with Sierra, who then gave them 90 days to build a playable prototype from a subset of the spec
• Still technically under NDA, so Tim can't share it publicly

References

• Tim Cain. YouTube video. https://www.youtube.com/watch?v=Lm0qhfquv74