How do I end the game?

How do you make it so when the player completes your game, the game ends?

You can do this with a textbox conditional. Enable the GAME section of the conditionals ("Always do the following"), and change "don't load/end game" to "game over".

With a script

You can also create an ending slide show as a sequence of textboxes, but you might want to use a plotscript instead. To end the game, just use the plotscripting command game over.

Note that if you attach a backdrop to a textbox and use wait for textbox immediately before game over, just before the player returns to the title screen the player will see the hero on the map for an instant. So you might want to use the show backdrop command instead.

plotscript, end the game, begin 
  play song (song:game over)
  show backdrop (2)
  show text box (45)
  wait for text box
  game over
end