There are only 2 duplicate characters in the menu font that GBA Script uses: there are 2 “:” and 2 “?” available, so these are the only easy choices of what to replace.
Why do I want to do this? To get the Boomerang icon in, for the throwing weapons, and a generic “bag” for the 3 Mix ingredients (these changes are seen in FFV Clean).
As soon as I repurposed the first “:” in byte postion $9B, I saw this when I tested it out:
Cool, cool. Very easy to test out this occurrence of the duplicate “:”… all I need to do is reset and game after a change and press A to get past the title screen!
So I patiently begin to look for all the places in the menu system that use the first “:” character, so I could make them all to use the second one “:” (it’s at $CF). I searched for bytes that were being Read by Mesen, to help narrow the search scope. And of couse, I commited to changing them one at a time.
Many of these dozens of test replacements didn’t glitch the game as it was loading— of course, they might’ve caused bugs while playing the game, though! Every time it didn’t change the “:” in the Load screen, I adjusted it back to $9B to prevent bugs. I only needed to find a handful of bytes in the rom that were getting read as a literal reference to that font character, and replace them with the other one.
Excitingly, some of these single-byte changes DID glitch the opening title screen sequence. Some entirely crashed the game and didn’t even show the title! Some of them skewed the title graphics, a little bit and allowed the game to start, tho. The byte at $038FDA made the dragon silhouette a funky rainbow gradient, and slightly warped the ripple of the logo. This was by far the coolest “miss” result. Every byte does something!
I eventually became a bit bored w doing this fishing game, so I tried a more elaborate search. Using the Mesen Tilemap Viewer, I clicked on the exact tile in the screen that was showing the 🔷 character represented by byte value $9B. I right clicked it and chose to View in Memory Viewer, and then I saw where it was sitting in V(ideo)RAM.
Since I learned that these games tend to have a character/color layout, I assumed that the $10 after the $9B was making it the white font color. The time values before and after it are dynamic, of course, but they are also getting the same color when shown on screen, and the bytes before and after the $9B10 pair also end in $10, so… I decided to search the entire rom to see if I could find any occurrences of these values WITHOUT the color (this hunch is informed by my work on the FFIV menu system).
How many times does the series $559B58 show up in the FFV rom?
Not even once!
After this dead end, I figured I’d try the most elaborate approach, even though I usually don’t get very far with this… setting a Break point in the game so that it pauses and shows the code that provides the on screen result. This is a bullseye when it works, but you often need to work backwards to find the original routine, and I often stumble on the way. Practice makes things easier, though…
It’s the very last option when you’re inspecting a tile in the Tilemap Viewer.
As soon as I set the Break point on this byte, the Debugger opened and showed me this: