Method the Third: Lerping Light Switches
Begin by covering your layout with black sprites, each Sprite completely covering a room. I would add a picture here, but all you're going to see is black.
Go to the Events and add two Events:
Now this means that when the Character is overlapping the Blacksprite, it fades to transparent (0 opacity) and when it is not it fades back to blackness. They need to be a subevent of For Each, otherwise the second event doesn't trigger.
The 0.1 is essentially the speed of the fade, the closer to 1 the faster it goes. Change it to what suits you.
Now you have these cute little rooms where the lights go on and off when you enter the room, which again is difficult to capture in a screen shot.
This method is best for a set up like this, with lots of small areas. If you're in a large environment then the hard edges feel unnatural. It could also be used for hidden areas, for example if you were to walk up next to a certain wall then the area would reveal inself.
It's easy to have multiple lights in this method, maybe an enemy or NPC triggers the lights as well, or after you push a button certain lights stay on permanently.