Editroid

Editroid is a level editor for the game Metroid. It allows editing the contents of screens, re-arranging screens on the map, editing items, palettes, the building blocks screens are made from, and more. It includes a built-in assembler for managing projects that include changes to the game's engine and to allow screen-load routines that can customize behavior or trigger changes for specific rooms.

The most recent full release of Editroid is 3.7.

An Alpha version of Editroid 4.0 has released, however it is buggy.

• Crash Course - For your first time with Editroid
• Data Structures - Detailed information on how the game world is built and how Editroid works with it.
• Doorways And Scrolling - Because things are never as easy as they should be
• Projects - Details on using the built-in assembler to do nifty things that Editroid doesn't support out of the box

The basic features of the user interface are explained here. Some self-explanatory items are omitted, and some more complex items have their own more detailed pages.

• Save And Play - Saves the ROM and opens it in the default program for .NES files.
• Expand Rom - Expands the ROM to create more space for graphics and data. Many Editroid features require an expanded ROM. The expansion process moves and reorganizes all sorts of data, so if the ROM has been modified in any way, it's best to create a backup before expanding the ROM.
• Create Backup - Creates a backup of the ROM currently open in the editor. The backup is created in the same directory with the filename being a time-stamp indicating when the backup was created (e.g. 2013_06_22_145936.nes).

• CHR Usage Editor - Used to specify which graphics banks are used for which levels. Graphics banks start at $40010 and are $1000 bytes (4 KB) each.

• Disable Selected Screen - “Disables” the screen currently selected in the editor. During gameplay, the view won't scroll into a screen that is disabled.
• Set Area Start Here - Specifies that, for the level it belongs to, the selected screen is the screen the player will respawn at for when he dies or enters a password. For Brinstar, this is also the screen the player will initially spawn at when the game begins.
• Generate Map - Creates a map of part or all of the game world that can be saved as an image.
• Pointer Explorer - Displays a listing of the location and raw data of various types of game data.
• Test Room - Launches a test ROM that will start the player in the selected screen with a specified set of equipment.

• Create Project - Creates a project for the ROM. This must be done before any project-based features are used. The project will be saved as a separate file with a .nes.proj extension.
• Edit Screen Load Code - Creates or edits a screen load routine for the selected screen. When a project is built, the routine will be executed when the screen is loaded into memory.
• Edit General Code - Edits the general code file. Any routines defined in this file will be accessible in screen load routines.
• Other Files - Advanced features to modify core ASM files or add and manage additional ASM files.
• Build - Runs the assembler and applies any other project-based modifications, creating a new ROM file.

• Display Alternate Palette - Displays graphics in the secondary area palettes. Applicable only to areas that have a palette swap.
• Display Physics - Outlines and colod-codes the objects in rooms to clearly show which parts of the rooms are solid, air, breakable, doorways, etc.
• Previous/Next CHR - Changes which graphics bank is used to display graphics. Useful for areas that use more than one tile set.

• Add/Remove - This menu allows the addition of objects to rooms, new rooms to areas, and new structures to be used in the creation of rooms (as well as the removal of all of the above).
• Screen Browser - Displays a dialog that allows the user to browse through thumbnails of all the screens for the current area.
• Structure Browser - Displays a dialog that allows the user to browse through thumbnails of all the screen objects available for the current area.
• Brinstar/Kraid/Norfair/Ridley/Tourian - When an empty map location is selected, these buttons appear and allow the user to activate the screen and edit it as a screen for the respective area.