Example Session: Using /design-system to Author a GDD

Context: Solo indie dev, week 3 of project. /map-systems already ran and produced design/gdd/systems-index.md. The movement system is listed as MVP tier, Foundation priority.

Starting State: - design/gdd/game-concept.md exists (survival-crafting game, 2D, Godot 4.6) - design/gdd/systems-index.md exists (15 systems identified, movement is first in design order) - No per-system GDDs written yet - No upstream dependencies for movement (it is the foundation)

Session Duration: ~60 minutes Turns: 14 Outcome: Complete design/gdd/movement-system.md with all 8 required sections written to file, ready for /design-review

Turn 1: User Invokes the Skill

User:

/design-system movement

Turn 2: Agent Loads Context and Presents the Plan

Agent (game-designer, via /design-system):

I'm loading context before we start:

• Read design/gdd/game-concept.md — survival-crafting, exploration-heavy, lone survivor stranded on alien planet
• Read design/gdd/systems-index.md — movement is Foundation / MVP, no upstream deps, downstream: combat, exploration, stamina
• No prior GDD found for movement — starting fresh

Technical Feasibility Pre-Check:

Domain	Signal
Engine	Godot 4.6 — CharacterBody2D with move_and_slide() is well-supported
Physics	Jolt is now the default in 4.6 — 2D movement unaffected, but note for future 3D work
Downstream risk	Stamina system listed as downstream dep — movement must expose a stamina callback hook

The GDD template has 8 required sections. We'll go one at a time: Overview → Player Fantasy → Detailed Rules → Formulas → Edge Cases → Dependencies → Tuning Knobs → Acceptance Criteria

I'll show you a draft of each section, you approve or revise, then I write it to the file before we move on.

Creating the file skeleton now with empty section headers — may I write design/gdd/movement-system.md with placeholders?

User:

Yes

Agent writes design/gdd/movement-system.md with 8 empty section headers.

Turn 3: Section 1 — Overview

Agent:

Section 1 draft — Overview:

The movement system is the player's primary interface with the world. It governs how the lone survivor walks, runs, rolls, and traverses alien terrain. Movement is physically grounded — the planet has heavier-than-Earth gravity, and the survivor is physically exhausted — but remains responsive enough to stay out of the player's way. The system feeds directly into exploration pacing, combat positioning, and the stamina system.

Does this capture what you want?

User:

Good but add something about the terrain — surfaces slow you down or have friction modifiers.

Agent:

Revised:

The movement system is the player's primary interface with the world. It governs how the lone survivor walks, runs, rolls, and traverses alien terrain. Movement is physically grounded — the planet has heavier-than-Earth gravity, and the survivor is physically exhausted — but remains responsive enough to stay out of the player's way. Terrain surfaces apply friction and speed modifiers (slick rock, sand, shallow water) that make navigation a meaningful skill. The system feeds directly into exploration pacing, combat positioning, and the stamina system.

May I write this to Section 1 in the file?

User:

Yes

Agent writes Section 1 to file.

Turn 4: Section 2 — Player Fantasy

Agent:

Section 2 draft — Player Fantasy:

The player should feel like a tired but capable survivor — not a superhero, not helpless. Early game movement is deliberate and taxing; the player earns fluency over time. When traversing alien terrain, the goal is careful navigation with moments of urgency (running from threats, leaping a gap). The fantasy is "I know this terrain" — every surface type becomes readable and manageable as the player internalizes the friction system.

Approve, revise, or change direction?

User:

Love it. Write it.

Agent writes Section 2 to file.

Turn 5: Section 3 — Detailed Rules

Agent:

Section 3 draft — Detailed Rules:

Base States: - Walk (default): Full directional control, moderate speed, low stamina drain - Run (hold Shift): Faster, medium stamina drain per second — cancels automatically when stamina hits 0 - Roll/Dodge (tap Space): Quick burst in movement direction, brief invincibility frames, high stamina cost (flat) - Idle: Zero movement input, stamina regenerates at full rate

Terrain Modifiers: - Normal ground: 1.0x speed multiplier, standard friction - Sand/loose soil: 0.8x speed, 1.1x stamina drain (harder to move) - Slick rock (wet): 1.1x speed, reduced stop friction (player overshoots) - Shallow water (ankle-deep): 0.7x speed, no friction modifier - Deep water: movement disable