Room Editor
This isn't bad for an evening's work!
Rooms are currently based on five layers:
Backdrop - Large tiles on the far wall of the scene like the wood walls here
Background - Actual platforms and walls that make up a level
Decoration - Items like the desk, bed, tables that the player can't interact with but give flavour to the surroundings
Objects - Interactive objects - things you can pick up, look at, use and so on. There are none in this scene just now, because I still have to work out how I'm going to do them! Placing them is easy enough, but loading and saving their attributes (whether they've been picked up already, what state they're in...) is going to be a more difficult challenge.
Foreground - The same as the decoration layer, but these will appear in front of the player and objects.
I also love how the outdoor tiles in the second half of that screenshot turned out when put together... somehow, I've managed to produce something that doesn't look dreadful.