And finished. Had several weird things happen this version to work around, as well as unexpected (read: braindead) semantic problems to deal with.

Anyway, nonflickering room objects are now added. Having some objects avoid flickering can help with making sure collisions register asap. (As soon as the object it reacts to gets swapped in)

One use, as demonstrated in this version, is castle gates/doors/etc that are locked. The black key does indeed unlock the castle and you can go inside. I've modified the layout of the realm somewhat. Modified colors so the rooms all look a bit different - if just to show that it can be set on per room basis. Playfield and background can both be changed.

A glitch I'd like to work out for a later version is with exiting castles. (Later on it'll be more than just exiting castles!)

You'll notice as you leave, for a single frame you're displayed at the top of the screen. I was hoping that wouldn't show up and the intialization to the proper X/Y would happen before you got displayed. Guess I misjudged. I'll probably consider a way to add it to the room data since the only time it makes a difference is when you're leaving rooms. Last thing I want to do right now is think of more code tho.

The gate's moving too fast right now but that's temporary. I haven't added the Game Tick code to divide some tasks across multiple frames. When I add that next version (it's the very next thing I'll be doing) It'll likely rise and drop quite a bit slower. And as a result it'll actually be possible to close the gate.

I may work more on held objects. I had an idea to have them reposition themselves with respect to you as you move. Since there's going to be several objects that can be carried like the black key, I want to make it into a routine I can call if possible. So we'll see how that goes.

After that I'll also make sure there's a way to drop what's held.