Some games get around this by updating that register in the middle of the screen (which I also do when I'm drawing the subscreen map), but with the other stuff I'm trying to display (multi-colored main character, multiple enemies, missiles, etc), I don't really have time to do that. (as a counter-point, see the game Super Cobra, where they manage to cram that all in along with updating the background, although they have some clever limitations on movement to simplify things very slightly)
|I've read bad reviews about this game, but I'm convinced the programmers are geniuses.|
ANYWAY, my solution in Anguna is just to force every screen to be symmetrical (other than doors/walls on the far edges, which I fake with the Ball object). This makes for slightly less interesting room layouts, but makes my life a lot easier. Except that my overall world design called for (at least) 2 rooms that broke that rule, and needed to be asymmetrical. I had punted thinking through the design of how I was going to make these rooms work, assuming I'd come up with something eventually.
And so I did.
The 2 rooms are mirror images of each other, but not symmetrical themselves. It was a place where the river turned a corner: