Game Design Fundamentals

Design theory, documentation, and player psychology for compelling games

Game Design Document (GDD)

One-Page GDD Template

# [Game Title]

**Genre**: [e.g., Roguelike Deckbuilder]
**Platform**: [e.g., PC, Mobile, Web]
**Target Audience**: [e.g., Casual puzzle fans, 18-35]

## Core Loop
[Action] → [Challenge] → [Reward] → [Progress]

## Unique Selling Point
What makes this different from similar games?

## Key Mechanics
1. [Primary mechanic]
2. [Secondary mechanic]
3. [Meta progression]

## Mood & Tone
[Art style, music, overall feel]

## Success Metrics
- Retention Day 1: 40%
- Retention Day 7: 20%
- Session length: 10-15 min

Full GDD Structure

1. Overview
   - Concept, genre, target audience
   - Platform, business model
   
2. Gameplay
   - Core mechanics
   - Controls
   - Game modes
   
3. Progression
   - Level structure
   - Unlocks
   - Difficulty curve
   
4. Story & World
   - Narrative
   - Characters
   - Lore
   
5. Art & Audio
   - Visual style
   - Music direction
   - SFX approach
   
6. Technical
   - Engine
   - Requirements
   - Multiplayer architecture
   
7. Monetization
   - Business model
   - IAP strategy
   
8. Timeline
   - Milestones
   - Release schedule

Core Loop Design

The Engagement Cycle

    ┌──────────────────────────────────────┐
    │                                      │
    ▼                                      │
[Action] ──→ [Challenge] ──→ [Reward] ──→ [Progress]
    │
    └── Player performs primary action

Examples

Player Psychology

Motivation Types (Self-Determination Theory)

Autonomy:   Let players make meaningful choices
Competence: Skill growth, mastery feeling
Relatedness: Social features, shared experiences

Flow State

        Difficulty
            │
   Anxiety  │   ╱ FLOW ZONE
            │ ╱
            │╱
    ────────┼──────── Skill
            │╲
            │  ╲ Boredom
            │

Goal: Keep players in the flow zone
- Too easy → Boredom
- Too hard → Anxiety/Frustration

Reward Psychology

Variable rewards > Fixed rewards (for engagement)
Immediate feedback > Delayed feedback
Earned rewards > Given rewards

Diminishing returns:
- 1st reward: 100% excitement
- 2nd same reward: 80%
- 3rd same reward: 60%
Solution: Rotate reward types

Game Balancing

Dynamic Difficulty Adjustment (DDA)

// Track player performance
const metrics = {
    deathRate: deaths / attempts,
    completionTime: avgTime,
    hitRate: hits / attempts
};

// Adjust difficulty
if (metrics.deathRate > 0.5) {
    enemyHealth *= 0.9;
    playerDamage *= 1.1;
} else if (metrics.deathRate < 0.1) {
    enemyHealth *= 1.1;
}

Balancing Formulas

Power curve:
  power = base * (1 + level * 0.1)

XP requirements:
  xpNeeded = baseXP * (level ^ 1.5)

Damage formula:
  damage = attack * (100 / (100 + defense))

Economy:
  Sink = Source (coins earned = coins spent over time)

Testing Approach

1. Start slightly overpowered → More fun data
2. Run simulations (AI plays 10,000 games)
3. Playtest with real users
4. Iterate based on metrics
5. Balance for average, accommodate extremes

Progression Systems

Horizontal vs Vertical

Vertical: Power increases (levels, stats)
Horizontal: Options increase (unlocks, sidegrades)

Healthy games: Mix of both
Avoid: Endless vertical (power creep)

Progression Types

Unlock Pacing

Early game: Fast unlocks (hook)
  - New thing every 2-5 minutes
  
Mid game: Steady unlocks
  - New thing every session
  
Late game: Mastery unlocks
  - Exclusive rewards for dedication

Monetization Ethics

Ethical F2P Principles

✅ Cosmetics only (no pay-to-win)
✅ Fair grind (achievable without paying)
✅ Clear pricing (no dark patterns)
✅ Battle pass (value over time)
✅ One-time "remove ads"

❌ Loot boxes with real money
❌ Energy systems that block play
❌ Aggressive FOMO tactics
❌ Hidden costs / currency obfuscation
❌ Targeting vulnerable players

Accessibility

WCAG for Games

Visual:
- Colorblind modes (8% of males)
- Scalable UI
- High contrast options
- Screen reader support (menus)

Motor:
- Remappable controls
- One-handed modes
- Auto-aim assist
- Adjustable timing

Cognitive:
- Tutorials
- Difficulty options
- Save anywhere
- Clear objectives

Accessibility Checklist

[ ] Colorblind simulation tested
[ ] Remappable controls
[ ] Subtitle options
[ ] Adjustable text size
[ ] Screen shake toggle
[ ] Difficulty presets
[ ] Skip tutorial option

Localization

Planning for L10n

- String externalization from day 1
- UI flexible for text expansion (+30% for German)
- Cultural sensitivity review
- Right-to-left (Arabic, Hebrew) support if needed
- Date/time/number formatting

Priority Markets

1. English (global)
2. Simplified Chinese (huge market)
3. Japanese (high ARPU)
4. Korean (competitive games)
5. German/French/Spanish (Europe)
6. Portuguese (Brazil)