Platforms Break Wall Shadows/Wall Placement

@rory_nutt 

The issues you bring up and what I saw in your vid are normal.  I see nothing there I haven't seen in my game. Imo, they are basically a quirk of the build system and due to how platforms work and how game lighting works.  Platforms are essentially a room all their own within a room, so indirect lighting like I see in your pic, will do odd things with shadows because of that and the fact they are a different height than the rest of the room.  It doesn't matter whether the platform is depressed or raised either.  And tbh, it's not really any different IRL buildings imo. The solution to deal with it in the game is usually to add additional lighting matching the ones in the room that is directly over the platform so the floor over the platform will be lit at the same level.  There will still be a little difference though no matter what you do due to the different heights.  Another contributing factor is the room design itself too.  How many light fixtures and window you have or objects that emit light also affect it so about all you can do to improve the situation is move things around or even change room dimensions until you something you can live with.  I know from my own experience, a lot of the time when I try to the lighting "just right", I end up just saying "good enough" and move on.  It's simply not worth the time and effort to get it perfect.  And if you don't already know, spandrels used inside rooms can cause a lot of the same issues for pretty much the same reasons platforms do. Even fences will do it in some cases.  What the effects are dependent mostly on how you've designed the build.

About the wall placement issues.  You said you placed platforms and then drew walls on top of them and you can place wall mounted options and get "can't do that" error message.  Again, that's because the platform is seen as separate room.  The way to get around it though a lot of the time is to not start drawing the wall on the platform.  Start the wall at least a tile away from the platform and draw it towards the platform.  If you watch how the wall places when you draw, the bottom of walls started on a platform edge will still be full height and taller than those of the surrounding room.  You'll most often see the edge of the platform at the wall base.  The ceiling though, will auto truncate that wall at the ceiling with no problem but wall mounted items will tend to get confused sort of because they are trying to place at the overall room's normal wall height locations rather than the higher platform's locations.  On top of that, not all wall mounted objects will be affected.  Some will work but others won't.  Bottom line to all this, you'll get a lot less of those errors with wall placed objects if you draw the walls around the edges of platforms starting a point that is level with the surrounding room's floor at least one tile away from the platform edge and draw them towards the platform.  Sometimes you have to get a little creative depending on how you are arranging things to do that.

Hope this helps.