User blog comment:Randomouscrap98/Adventures in Village 1/@comment-14600979-20130820232656/@comment-9531161-20130823025446

Lumage, was that last post yours? I wasn't sure, so I didn't respond. I'm sorry!

Since your walls are just BG tiles, you could use BGREAD to get what character you're about to run into. Then just keep a table of which BG characters are obstacles and whatnot, and do a quick lookup in the table (if it's an array, just make it the index for instant access) to see if you're allowed to walk through it.