I need some help with Hyrule Magic

Things aren't very intuitive. There's lots of features that I don't know what they do. For example, when normal editing of the overworld, I can only edit 2x2 tile sized of the world rather than single tiles. However, when I click a checkbox called "Overlay" I can edit single tiles. However, after saving the ROM, and playing the game, those tiles do not actually appear in the game. When I add tiles in overlay mode, how do I make the game load them properly?

You don't edit the "overlay". The "overlay" button in HM is only what will be additionally loaded onto the actual overworld with some additional ASM (ie event). If you want to edit the overworld, you leave the overlays, as well as backdrops (view into the valley when on Death Mountain) and also other additional effects, such as fog or rain.
Thus overworld is BG1 (normal), fog and rain is BG2 (loaded onto), button overlay in HM is BG3 (loaded onto fixed after an ASM event - so obviously will not appear in the game, since no ASM is given like pull switch or open with medallion etc).

However editing the overworld is not so easy. You draw with the big tiles (32x32) which you choose on the right. However editing the middle tiles (16x16 pixels) means you can not draw with them. You need to use 4 middle tiles to fill up 1 big tile and then draw with big tiles. The smallest tiles (8x8) a.k.a. GFX is loaded into the middle tiles. In this process you need to also choose gfx orientation (mirrored etc) as well as palette etc. Thus GFX (8x8) < middle tiles (16x16) < big tiles (32x32). 4 gfx tiles is one middle tile, 4 middle tiles is one big tile, drawing of overworld is with big tiles.

This is how the game is programed. Although Nintendo probably made the overworld with middle tiles separately and then used programs to auto-make the big tiles. The final result can not be reverse engineered (thus you can not draw with middle tiles), at least not with HM.

So overworld editing is not something you want to start with. Indoors is much easier to edit, since it is not GFX drawing based, but rather "element" based, which was quite revolutionary achievement for its time, since indoors was usually also GFX drawing based like overworld (like in Zelda Ancient stone tablets for instance).

Puzzledude wrote:You don't edit the "overlay". The "overlay" button in HM is only what will be additionally loaded onto the actual overworld with some additional ASM (ie event). If you want to edit the overworld, you leave the overlays, as well as backdrops (view into the valley when on Death Mountain) and also other additional effects, such as fog or rain.
Thus overworld is BG1 (normal), fog and rain is BG2 (loaded onto), button overlay in HM is BG3 (loaded onto fixed after an ASM event - so obviously will not appear in the game, since no ASM is given like pull switch or open with medallion etc).

However editing the overworld is not so easy. You draw with the big tiles (32x32) which you choose on the right. However editing the middle tiles (16x16 pixels) means you can not draw with them. You need to use 4 middle tiles to fill up 1 big tile and then draw with big tiles. The smallest tiles (8x8) a.k.a. GFX is loaded into the middle tiles. In this process you need to also choose gfx orientation (mirrored etc) as well as palette etc. Thus GFX (8x8) < middle tiles (16x16) < big tiles (32x32). 4 gfx tiles is one middle tile, 4 middle tiles is one big tile, drawing of overworld is with big tiles.

This is how the game is programed. Although Nintendo probably made the overworld with middle tiles separately and then used programs to auto-make the big tiles. The final result can not be reverse engineered (thus you can not draw with middle tiles), at least not with HM.

So overworld editing is not something you want to start with. Indoors is much easier to edit, since it is not GFX drawing based, but rather "element" based, which was quite revolutionary achievement for its time, since indoors was usually also GFX drawing based like overworld (like in Zelda Ancient stone tablets for instance).

So when you say an ASM event, do you mean ANY ASM event, like I can just add a pull switch (even if it has corrupt graphics in the overworld), and then by pulling it it will display whatever graphics are in the overlay?

Also, how do I find out what event triggers a particular overlay? For example, I am looking at a screen in HM right now, for area 0x10 of the overworld (left side of the map, one screen south of the woods). When I display the overlay, I see near the left side of the screen, there's an overlay for a stairway into an underground area. I would like to know what event displays these this stairs overlay, so I can activate it and go down and see what's down those stairs.