Here's one way to do it.
There is a script that skips the title screen and takes you to a map of your choice. Find it, and make it transport you to the following map:
make an empty map(you should see only white space on it), and put the title picture as its panorama. use event on autorun to bring up the menu: new game, continue , shutdown. then just add your fog to the map.
if player selects New Game, transport to the starting town.
if shutdown, use a script call saying: $scene = nil
if Continue, use a script call saying: $scene = Scene_Load.new
But, if there are no saved files yet, use another menu: only new game, shutdown.
Here's how to have a switch telling you if there are any save files:
Place this in a script call comand, and it'll be OFF if no save file exist. You may wanna change the switch number from 1 to something else.
[rgss]
#if a save file exists
for i in 0..3
if FileTest.exist?("Save#{i+1}.rxdata")
$game_switches[1] = true
end
end
[/rgss]