let rec loop n = async{
        if n <> 0 && !running then
            Game.progressGame gameBoard GUI.CellCount
            drawGameBoard()
            do! Async.Sleep(GUI.Timer)
            return! loop (n-1)
        else
            GUI.btnRun.Text <- "Run"
            running := false
    }
    GUI.btnRun.Click
        |> Observable.add(fun _ ->
                            GUI.btnRun.Text <- if !running then "Run" else "Stop"
                            running := not !running
                            if !running then
                                let a, out = System.Int32.TryParse(GUI.txtTimes.Text.Trim())
                                if out > 0 then
                                    Async.StartImmediate(loop out)
                                else
                                    Async.StartImmediate(loop -1))