The first thing you do is to create a new game file. There is a game template in the framework so you can create it with the following steps.

1. Install the Xcode Project Template for the game framework
   • You can download it from here
2. Create a new Xcode project with RubyCocoa Game template
   • Choose "File" -> "New Project" at the menu bar
   • Select "Cocoa-Ruby Game Application"
     
     
   • Enter the name of a new project
     
     
3. Add a new game file with the game file template
   • Open the "Classes/ruby/games" group at the left pane
     
     
   • Right-click the "games" group
   • Select "Add" -> "New File" at the pop-up menu
   • Select "RubyCocoa Game Template"
     
     
   • Enter the name of a new file (say TankGame.rb)
     • The base name of the filename is used to replace the class names

That's it. Now you have a new file "TankGame.rb" in the games group. By double-clicking the filename, you can see the code below:

require 'Game'
require 'State'
require 'Event'
require 'View'
require 'Utility'

class TankGameModel
  def init()
    # this method is called when Application is launched.
    # It is also called when TankGamePlayingState 
    # becomes the current state
    # do some initialization here
  end

  # Add some methods here
end

class TankGamePlayingState < State
  # define your timer IDs here
  MYGAME_TIMER = 1000

  def enter()
    super()
    @model.init()

    # Define context dependent event handlers
    # Each handlers are defined in a form of [EventType, Content, Proc object]
    # See KeyEvent.rb, MouseEvent.rb and TimerEvent.rb for event specific info
    # Other game's source code would also help you
    contexts = [[TimerEvent::Fired, MYGAME_TIMER, proc {|id| tick() }]]
    contexts.each {|context| EventContext.addContext(*context) }
    @timer = TimerEvent.new(0.1, true, MYGAME_TIMER)
  end
  
  def tick()
    # do something when timer event occurs
    return true
  end
  
  # add some event handlers or context handlers here
end

class TankGameView < View
  def notifyStateDidChange()
    # If you need some initialization process,
    # Override notifyStateDidChange and write what you want here.
    # If you don't need any initialization process for this view class,
    # Just remove this method
    ColorCollector.init(['black'])
  end    

  #
  # This method is called from MiniGamesView
  # 
  def drawRect()
    NSColor.blackColor.set
    NSRectFill(@bounds)
    
    # Use ShadowMaker module to easily draw shadow for objects
    setShadow(NSColor.lightGrayColor, [6.0, -6.0], 3.5, 0.6)
    # Use TextMaker module to easily draw Text
    drawCenterizedText("Draw Something", 70, NSColor.whiteColor)
  end
end

class TankGame < Game
  def initialize()
    @bindings = [[TankGamePlayingState, TankGameModel, TankGameView]]
    @initialState = TankGamePlayingState
  end
  def self.title() "TankGame" end
  def self.titleImage() nil end # return the name of an image here
end

Thanks to the Xcode template, you don't have to copy the template nor replace the class names. That's helpful isn't it?

Run It Anyway

The game template actually works as it is so why don't you run it? Press the "Build & Go" button (or Command-R key) at the project window. Then you see the main title of MiniKidsGames.

Select TankGame and hit the space key (at this point, you didn't make any title image for this game so the default title image is used.) You see a message "Draw Something." This game does nothing but draw this message and quit. Press "Ctrl-Q" to go back to the main menu.