Simplified and cleaned up version of http://patterngazer.blogspot.com/2011/10/snaky-tribute-to-stuart-in-scala-with.html#comments

Game.scala

package com.promindis.game.snake.stm

import akka.actor.{ActorRef, Actor}
import java.awt.{Dimension, Graphics2D}
import java.awt.event.{ActionEvent, ActionListener}
import swing._
import swing.Dialog._
import swing.event.Key._
import swing.event.KeyPressed


object Game extends SimpleSwingApplication {
  val boardRef = Actor.actorOf(new BoardActor()).start()
  val board = new Board(boardRef)
 
 
  class Board(boardRef:ActorRef) extends Panel {
    var doPaint: ((Graphics2D) => Unit) = (onGraphics) => {}
    preferredSize = new Dimension(GraphicConverters.converted(World.width), GraphicConverters.converted(World.height))
    focusable = true
 
    override def paintComponent(onGraphic: Graphics2D) {
      super.paintComponent(onGraphic)
      doPaint(onGraphic)
    }

    def apply(snake: List[ScreenLocation], apple: ScreenLocation) {
      def paintPoint(screenLocation: ScreenLocation, color: Color, onGraphics: Graphics2D) {
        onGraphics.setColor(color)
        onGraphics.fillRect(screenLocation.x, screenLocation.y, screenLocation.width, screenLocation.height)
      }

      doPaint = (onGraphics: Graphics2D) => {
        paintPoint(apple, new Color(210, 50, 90), onGraphics)
        snake.foreach {
          paintPoint(_, new Color(15, 160, 70), onGraphics)
        }
      }
      repaint()
    }


    listenTo(keys)
 
    reactions += {
      case KeyPressed(source, key, modifiers, location) =>
        boardRef ! ReceivedPressed(key)
    }
  }
 
  def displayMessage(text:String) {
    boardRef ! ShowMessage(text)
  }

  case class ShowMessage(text:String)
 
  case class ReceivedPressed(keyCode:Value)
 
  case class Updated(snake:List[WorldLocation], apple:WorldLocation)


  class BoardActor() extends Actor {
    import GraphicConverters._
    import World._
 
    val directions = Map[Value, WorldLocation](
      Left -> Direction.Left,
      Right -> Direction.Right,
      Up -> Direction.Up,
      Down -> Direction.Down
    )
 
    protected def receive = {
      // update board object in enclosing object with new coordinates via implied apply()
      case Updated(snake, apple) =>
        board(converted(snake), converted(apple))

      case ReceivedPressed(key) =>
        Entities.updateSnakeDirection(directions(key))

      case ShowMessage(text) =>
        showMessage(parent = board, message = text)
    }
  }
 
  def update(list: List[WorldLocation], location: WorldLocation) {
    boardRef ! Updated(list, location)
  }
 
  def top = new MainFrame {
    title = "Snake"
    contents = new FlowPanel() {
      val timer = new javax.swing.Timer(100, new ActionListener() {
        def actionPerformed(e:ActionEvent) {
          Entities.updatePositions()
        }
      }).start();
      contents += board
    }
    pack()
  }
}