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Daniela Petruzalek
Daniela Petruzalek

Senior Developer Relations Engineer at Google

Writing about AI agents, Go, and Cloud.

Game Design Document (GDD) Template #

Game Title: [Insert Title] Target 2D Genre: [e.g., Top-Down RPG, Bullet-Heaven, Shmup, Turn-Based Tactics, Deckbuilder, Puzzle, Visual Novel, Platformer, Arcade] Camera Perspective & Spatial Model: [e.g., Top-Down 2D Plane, Orthogonal/Isometric Grid, Card Table / UI Canvas, Narrative Stage, Side-View Arena] Simulation Model: [e.g., Real-Time Continuous ($\Delta t$), Turn-Based Phases, Discrete Grid-Step, Event/Dialogue-Driven] Target Platform: Desktop (Windows/macOS/Linux) & WebAssembly (Browser / Google Cloud Run) Target Aspect Ratio & Virtual Canvas: [e.g., 16:9 Widescreen (320x180, 640x360, or 1280x720) / 4:3 Retro] Author / Lead Designer: [User Name / Agent]

1. Executive Summary & Elevator Pitch #

  • Elevator Pitch: [1–2 sentence hook describing the core player fantasy, 2D genre, and primary mechanic twist]
  • Core Inspiration: [e.g., Vampire Survivors meets Chess, Slay the Spire with spatial grid positioning, Into the Breach, Celeste, Ace Attorney]
  • Target Audience & Mood: [e.g., High-intensity bullet-hell survival, cerebral turn-based strategy, cozy narrative mystery]

2. Core Gameplay Loop, Simulation & Mechanics #

  • Primary Gameplay Loop: [Step-by-step description of player decision/action -> systemic challenge -> feedback/progression cycle]
  • Spatial & Simulation Rules:
    • Movement / Interaction Topology: [e.g., Free 360° vector movement, 8-way grid stepping, pointer card drag-and-drop, dialogue choice selection, or gravity-based platforming]
    • Player Abilities / Actions: [e.g., Auto-fire & dash, cast card from hand, command squad unit on tile, rotate puzzle cluster, present evidence]
    • Systemic Challenges / Opponents: [e.g., Swarming enemy waves, enemy turn AI intent, mana/turn limits, board space constraints, branching dialogue locks]
  • Win & Loss Conditions:
    • Win Condition: [e.g., Surviving 10-minute swarm & defeating final boss, clearing Act 3 boss node, solving all grid constraints, reaching True Ending]
    • Loss Condition: [e.g., Player/Party HP reaches 0, command center destroyed, deck/moves exhausted, timer expires]

3. Controls & Input Mapping Scheme #

  • Primary Input Devices: [Mouse/Pointer, Keyboard, Gamepad, Mobile Touch]
  • Default Control Scheme:
    Logical ActionKeyboard / MouseGamepad ButtonTouch Gesture
    ActionNavigate / MoveWASD / Arrows / Mouse CursorLeft Stick / D-PadVirtual Stick / Drag
    ActionPrimary / ConfirmSpace / Enter / Left ClickButton South (A / Cross)Tap Target / Card
    ActionSecondary / CancelShift / Right Click / BackspaceButton East (B / Circle)Two-Finger Tap
    ActionContext / InspectTab / E / Middle ClickButton North (Y / Triangle)Long Press
    ActionPauseEscape / PStart / OptionsPause Icon Button

4. Visual Style & Asset Pipeline Strategy #

  • Aesthetic Direction: [e.g., 16-bit Pixel Art, Crisp Tactical Vector UI, Hand-Drawn Visual Novel Portraits, Neon Cyber Geometry]
  • Selected Visual Pipeline Mode (explicitly chosen during /grill-me): [Pure-Code Procedural | AI-Generated Media | Hybrid Pipeline]
    • Pure-Code Procedural (procedural-art) Assignments: [e.g., UI 9-slice panels, grid overlays, projectiles, particle pools, Kage post-processing shaders]
    • AI-Generated Media (nano-banana — gemini-nano-banana-2.1) Assignments: [e.g., Character sprite sheets, visual novel portraits, deckbuilder card art, seamless tilesets, background illustrations]
  • Sprite Slicing & Animation (sprite-animation):
    • Animated Entities & States: [e.g., Top-down unit (idle, walk, cast, hit, defeat), card sheen/flip states, or character portrait expressions (neutral, happy, shocked)]

5. Audio & Soundscape Pipeline Strategy #

  • Selected Audio Pipeline Mode (explicitly chosen during /grill-me): [Pure-Code Procedural | AI-Generated Music | Hybrid Pipeline]
  • Background Music (BGM):
    • Style, Tempo & Mood: [e.g., 135 BPM dark synthwave, 85 BPM chill tactical lo-fi, 150 BPM YM2612 6-channel chiptune]
    • BGM Engine: lyria (lyria-3.5 / lyria-3-pro-preview or lyria-3-clip-preview 44.1 kHz stereo) OR procedural-composer (pure-code 6-channel PCM synthesis)
  • Sound Effects (SFX):
    • Required SFX Triggers: [e.g., UI hover/confirm, card draw/play, attack impact, level-up chime, alarm stinger, victory/defeat fanfare]
    • SFX Engine: procedural-composer (4-byte aligned 16-bit stereo PCM synthesized waveforms, FM sweeps, ADSR envelopes, and LPF/HPF/bitcrush post-processing)

6. Scene Flow & UI / HUD Layout #

  • Scene State Machine: Boot -> Title / Main Menu -> Gameplay / Encounter -> Overlay (Pause / Deck / Inventory / Dialogue) -> Victory / Game Over
  • HUD & UI Regions:
    • Displayed Information: [e.g., HP/Mana orbs, turn order timeline, wave timer & XP bar, hand of cards, dialogue speaker box]
    • Screen Anchoring: [e.g., Top-Left (Player Status), Top-Right (Minimap/Wave), Bottom-Center (Card Hand / Action Bar / Dialogue Box)]

7. Technical Scope & Ebitengine Architecture Notes #

  • Core Ebitengine Subsystems (ebitengineer):
    • Spatial / Collision System: [e.g., Uniform Spatial Hash (bullet-heaven/shmup), Orthogonal/Axial Grid Coordinates (tactics/puzzle), UI Hit-Testing Rects (deckbuilder/VN), or AABB Raycast (platformer/top-down RPG)]
    • World / Encounter Representation: [e.g., Autotiled Tilemap, Procedural Arena, Directed Acyclic Encounter Graph, Dialogue State Graph]
    • Zero-Allocation Hot Loop: Pre-allocated entity/particle slices and cached ebiten.DrawImageOptions in Update()/Draw()
    • Persistence / Backend: [e.g., Local JSON/IndexedDB save state or Cloud Run REST leaderboard]