Code: 
def command_new_game
  init_new_game()
  start_at()
end

def command_credits
  init_new_game
  start_at(1,1,1) #1 ist Map mit Credits!
end

def command_minispiel
  init_new_game
  start_at(1,1,2) #2 ist Map mit Minispiel
end

def init_new_game()
  # Play decision SE
  $game_system.se_play($data_system.decision_se)
  # Stop BGM
  Audio.bgm_stop
  # Reset frame count for measuring play time
  Graphics.frame_count = 0
  # Make each type of game object
  $game_temp          = Game_Temp.new
  $game_system        = Game_System.new
  $game_switches      = Game_Switches.new
  $game_variables     = Game_Variables.new
  $game_self_switches = Game_SelfSwitches.new
  $game_screen        = Game_Screen.new
  $game_actors        = Game_Actors.new
  $game_party         = Game_Party.new
  $game_troop         = Game_Troop.new
  $game_map           = Game_Map.new
  $game_player        = Game_Player.new
  # Set up initial party
  $game_party.setup_starting_members
end

def start_at(x=$data_system.start_x, y=$data_system.start_y,map_id=$data_system.start_map_id)
  # Set up initial map position
  $game_map.setup(map_id)
  # Move player to initial position
  $game_player.moveto(x,y)
  # Refresh player
  $game_player.refresh
  # Run automatic change for BGM and BGS set with map
  $game_map.autoplay
  # Update map (run parallel process event)
  $game_map.update
  # Switch to map screen
  $scene = Scene_Map.new
end
kurzum: erst mit init_new_game das Spiel starten, dann mit start_at(x,y,map_id) zur jeweiligen Position der Map teleportieren.