The
combo editor allows you to edit the combos for each level of Metroid. The combo
editor can be found under the "Special Tools" menu. Once you have
finished editing combos, close the editor and the changes you have made will be
reflected in the main window.
What Is A Combo?
A combo is simply a combination of four graphics tiles into a single larger graphic. 8x8 graphics tiles are placed two wide and two tall to create a 16x16 combo, and these combos are the building block of "structures," or the objects that are used to fill the screen.
In addition to its graphical representation, a tile has physical properties too. Some are solid, some can be passed through, and some can be destroyed. There are also two special tiles that are meant to be used for doorways.
How To Use The Editor
First, select the level for which you would like to edit combos. Each level has its own set of combos. You can also select a palette to view the combos with by using the buttons on the lower left corner of the window. The right-most button in the palette selector alternates between the two palette sets tables available for the current level.
Combos are displayed on the right, tiles on the left. To edit combos, select a tile to paint with and use the mouse to apply the tile to combos. When a combo is changed, every instance of this combo is modified, which means that each structure that contains the combo will be modified.
The number and physical properties of the selected tile are displayed below the tile selector. The selected tile is displayed with a white rectangle around it. To grab a tile from a combo, right-click on the tile in the combo editor. It will be selected in the tile selector and its physical properties will be displayed (this is a good way to see whether a pre-existing combo is solid, passable, or breakable).
Beyond a certain point the data will appear to be gibberish. This is actually ROM data that is not meant to represent combos but is being interpreted as combos. Theoretically, these could be used in structures, but in the original game they are not, and editing this data through the combo editor will most likely corrupt the ROM. If you aren't sure of what a combo is it is best to not edit it.