Map Editor
If you run the game with the editor command-line parameter (Link's Awakening DX HD.exe editor) the in-game map editor will be enabled. If you run the game from Visual Studio, this flag should be applied automatically in this fork.
To access the map editor, enter the game world and press Escape. You should get a screen similar to this:
On this screen, you can hover your mouse over any tile in the map, and if you press Escape again you will be instantly teleported to that location.
Currently, it is very easy to brick the game by removing the wrong thing or spawning some boss monsters, so make sure to frequently commit changes to your Data directory where map files are stored. A common symptom that something has gone wrong is randomly getting photo events the second you step into the overworld.
Saving changes is done with the Save... button near the top-left of the screen. Changes made to Tiles update immediately, while changes made to Objects require you to exit / enter the map again to apply.
This one is used to edit the basic terrain. You add tiles by left-clicking them and remove them by right-clicking. To bring up a palette and select a tile, press and hold the Ctrl key.
Edits map objects like enemies, trees, triggers, doors and so on. If you've ever used a 2D map editor before these are mostly familiar, and you can use the existing game as a reference for how individual objects work.
Used the same way as the tile editor, left-clicking will place an object and right-clicking will remove it. To bring up a palette and select an object, press and hold the Ctrl key.
This mode allows you to select individual objects on the map and move them or edit their properties, such as what rooms a door should lead to or what song a music object should play. The properties show up on the right side of the screen when you select an object.
