Exiting Parts Of A Game

global ExitGame = 0

while not ExitGame

whattodo = MenuScreen()
if whattodo = 1
 DoGame()
end if
ShowHighScores()

wend

function MainMenu()

while not exitfunc
 if keyhit(1)
  exitfunc = 1
  exitgame = 1
  return 0
 end if
 if keyhit(57)
  exitfunc = 1
  return 1
 end if
end function