Game Generator

Game Generator

Assists in generating valid GameSpec JSON + Lua scripts for the AI Game Platform.

When to Use

• User requests a new game ("create a platformer game")
• User wants to add features ("add enemies that patrol")
• User wants to modify Lua scripts ("make the player jump higher")
• User asks about game mechanics ("how do I implement collectibles?")

Instructions

1. Understand the Request

Identify the game type:

• FPS: First-person shooter with mouse look
• 2D Side-Scroller: Horizontal movement, jumping
• 3D Platformer: Top-down or angled view, WASD movement

2. Generate GameSpec Structure

{
  "meta": { "title": "Game Title", "version": "1.0.0" },
  "players": { "min": 1, "max": 1, "spawn_points": [{ "x": 0, "y": 1, "z": 0 }] },
  "worlds": [{
    "id": "world-1",
    "name": "Main World",
    "environment": {
      "ambient_light": { "color": "#ffffff", "intensity": 0.5 },
      "directional_light": { "color": "#ffffff", "intensity": 1, "position": { "x": 10, "y": 10, "z": 10 } }
    },
    "objects": [/* GameObjects */]
  }],
  "scripts": [/* Lua scripts */]
}

3. Create GameObjects

Each GameObject needs:

• Unique ID: "obj-player-1", "obj-enemy-1"
• Transform: position, rotation (radians), scale
• Components: mesh, light, or camera
• Optional script_id: Reference to Lua script

Mesh Component (Required for Visuals)

{
  "type": "mesh",
  "properties": {
    "geometry": "box|sphere|plane|cylinder",
    "color": 0xff0000,
    "width": 1, "height": 1, "depth": 1,
    "hasCollision": true,
    "collisionShape": "box|sphere|auto",
    "isTrigger": false
  }
}

IMPORTANT: Set hasCollision: true for physics interaction!

Camera Component

{
  "type": "camera",
  "properties": {
    "fov": 75,
    "isMainCamera": true,
    "usePointerLock": false  // true for FPS, false for 2D/platformer
  }
}

4. Write Lua Scripts

Essential Pattern for Transform Updates

function on_update(dt)
  -- ALWAYS use this pattern:
  local pos = gameobject.transform.position
  pos.x = pos.x + speed * dt
  gameobject.transform.position = pos  -- Must reassign!
end

Input Handling

function on_update(dt)
  if not input then return end  -- Optional safety check
  
  if input["w"] or input["arrowup"] then
    -- Move forward
  end
  if input[" "] then  -- Space key
    -- Jump
  end
end

Available Keys:

• input["w"], input["a"], input["s"], input["d"]
• input["arrowup"], input["arrowdown"], input["arrowleft"], input["arrowright"]
• input[" "] (space), input["shift"], input["control"]

Jump with Edge Detection

local velocity_y = 0
local was_space_pressed = false

function on_update(dt)
  if not input then return end
  
  local is_space_pressed = input[" "] == true
  if is_grounded and is_space_pressed and not was_space_pressed then
    velocity_y = jump_force
  end
  was_space_pressed = is_space_pressed
  
  velocity_y = velocity_y + gravity * dt
  pos.y = pos.y + velocity_y * dt
end

Find Other GameObjects

function on_update(dt)
  local player = find_gameobject("Player")
  if player then
    local dx = player.transform.position.x - gameobject.transform.position.x
    -- Use dx for AI, camera following, etc.
  end
end

Collision Callbacks

function on_collision(other)
  -- Solid collision (walls, floor)
  if other.name == "Wall" then
    print("Hit wall")
  end
end

function on_trigger_enter(other)
  -- Trigger collision (items, goals)
  if other.name == "Coin" then
    print("Collected!")
  end
end

5. Common Patterns

2D Side-Scroller Player

local velocity_y = 0
local gravity = -15
local jump_force = 7
local move_speed = 5
local is_grounded = false
local was_space_pressed = false

function on_update(dt)
  if not input then return end
  
  local pos = gameobject.transform.position
  
  -- Horizontal movement
  if input["arrowleft"] or input["a"] then
    pos.x = pos.x - move_speed * dt
  end
  if input["arrowright"] or input["d"] then
    pos.x = pos.x + move_speed * dt
  end
  
  -- Jump
  local is_space_pressed = input[" "] == true
  if is_grounded and is_space_pressed and not was_space_pressed then
    velocity_y = jump_force
    is_grounded = false
  end
  was_space_pressed = is_space_pressed
  
  -- Gravity
  velocity_y = velocity_y + gravity * dt
  pos.y = pos.y + velocity_y * dt
  
  -- Ground check
  if pos.y <= 0.6 then
    pos.y = 0.6
    velocity_y = 0
    is_grounded = true
  end
  
  gameobject.transform.position = pos
end

FPS Mouse Look

local rotation_y = 0
local mouse_sensitivity = 0.002

function on_update(dt)
  if mouse_movement then
    rotation_y = rotation_y - mouse_movement.x * mouse_sensitivity
  end
  
  gameobject.transform.rotation.y = rotation_y
end

Camera must have: "usePointerLock": true

Enemy Patrol

local patrol_distance = 3
local start_x = 0
local direction = 1
local speed = 2

function on_start()
  start_x = gameobject.transform.position.x
end

function on_update(dt)
  local pos = gameobject.transform.position
  pos.x = pos.x + direction * speed * dt
  
  if pos.x > start_x + patrol_distance then direction = -1 end
  if pos.x < start_x - patrol_distance then direction = 1 end
  
  gameobject.transform.position = pos
end

Collectible Item

local rotation_speed = 3
local collected = false

function on_update(dt)
  if collected then
    gameobject.transform.position.y = -100  -- Hide
    return
  end
  
  local rot = gameobject.transform.rotation
  rot.y = rot.y + rotation_speed * dt
  gameobject.transform.rotation = rot
end

function on_trigger_enter(other)
  if other.name == "Player" and not collected then
    collected = true
    print("Collected!")
  end
end

Checklist

Before generating GameSpec:

• All GameObjects have unique IDs
• Main camera exists with isMainCamera: true
• Camera has correct usePointerLock (true for FPS, false for 2D)
• Lights are configured (ambient + directional/point)
• Collision objects have hasCollision: true
• Triggers have isTrigger: true
• Script IDs reference existing ScriptDefinitions
• Lua scripts use correct Transform update pattern
• Input handling includes safety check if not input then return end

Common Mistakes to Avoid

1. ❌ gameobject.transform.position.x = x + 1 → ✅ Use local variable pattern
2. ❌ Forgetting hasCollision: true → Objects pass through each other
3. ❌ usePointerLock: true for 2D games → Breaks keyboard input
4. ❌ Jump without edge detection → Continuous jumping
5. ❌ Not multiplying by dt → Frame-rate dependent movement

Reference

For detailed API reference, see:

• Lua API Documentation
• GameSpec Type Definitions
• Template Examples