feat: add default gamesystem uses inside mainmenu

examples/mainmenu/init.lua

@@ -85,6 +85,8 @@ end
 function MainMenu:draw()
   love.graphics.setColor(.3,  .1, .4, 1)
   love.graphics.rectangle("fill", 0, 0, 424, 240)
+  utils.graphics.resetColor()
+  love.graphics.print(math.floor(game.playtime), 8, 8)
 end
 
 -- WIDGETS
@@ -142,6 +144,7 @@ function ExitWidget:new(scene, menu)
 end
 
 function ExitWidget:action()
+  game:write()
   love.event.quit()
 end