Awesome, it's great to hear you've had fun playing it

To be honest, I'm not entirely sure now if that (re: Anazar's dungeon) was intended. I also noticed it during my testing of the port, and I can't remember if that was a testing shortcut that I forgot to close, but I decided to leave it as it was.
Most of the no-clip fake walls are mandatory, in that you need to find them to get to bosses, etc. so you've probably found most/all of them. Although I think there are 1 or 2 underground caves/temples that appear to have nothing in them, but have a room hidden behind a fake wall. But yes, pretty much trial and error trying to walk through walls. Is it too frustrating to find like that? Should I add a small visual clue? Or do you think it's good to leave it as is?
I also considered adding in difficulty levels, but didn't end up doing it. If I did, I was thinking something along the lines of:
Easy - Reduced damage from enemies, reduce HP for enemies.
Normal - No change to current game.
Hard - Same enemy damage & HP, but Gold death penalty to be 1/2. Maybe increase maximum enemies on screen from 4 to 6?
Hardcore - If you die, you have to restart (like in Minecraft, Diablo, etc.)
Peaceful - Enemies don't do any damage, player can free walk anywhere except out of the map boundaries. This mode would only be available once Banchor has been defeated, if the player wanted to make sure they've fully explored everything without having to deal with enemies.
If I ever get around to doing a 4-bit colour update at some stage, I'll probably add in the above as well.