Hmm...well it seems simple, and in some ways it is, but it becomes
really complicated just because of an inherent problem with
translating japanese (which is the language these video games were
originally made in) to english.
But, anyways, what you start with is a ROM in japanese.
Then, the first thing depends on whether the ROM has english
characters in it or not. If it doesn't, like Final Fantasy II, III, and V,
you must first input english tiles to the ROM over some of the existing
japanese character tiles. Then, to make a script and be able to tell what
text you are editing at a given time, you must find out what hex codes are
used in the game's program to represent each letter's tile. (btw, this
actually can be done before the step one. You can make a japanese script,
then put english characters in, and then start editing.)
Figuring out these hex codes is the hardest part of the first step in ROM translation.
But it is possible =)
After figuring out these codes, and making a script, you can start editing.
It seems like it would be all clear after that, but it's not...
Because of that inherent problem I mentioned earlier...
The problem is, the differences between the japanese and english languages.
In english, we use an alphabet with 52 characters. (26 lowercase, 26 capitals.)
But, japanese uses two syllabaries with over 70 characters each (including the dakuten/handakuten),
(these syllabaries are called hiragana and katakana). Plus an ideographic
system known as kanji, which means chinese characters.
All in all, this means that japanese can write things in many less characters
than english, because each of their characters represents MORE.
For instance, in japanese, 'bukiya' means 'weapon store', but in japanese,
bukiya is only 3 characters!! (either kana or kanji.) Whereas in english,
weapon store is *12* characters!!! (yes, and not only do the japanese
characters make it hard, but as you can see bukiya is a much shorter word
than weapon store anyways.)
That means, in the japanese ROM, bukiya could be stored using only
3 bytes, but in a translation weapon store would require 12 bytes.
That obviously is a problem.
And so, we must find ways of working around this problem, such as
expanding ROM size to give us more space for the english words or
using special codes or tiles to make 2 english letters with 1 byte.
And of course, since japanese can write things in much smaller
spaces...the windows in japanese games don't have to be that large!!
So, in FFIII, the window for battle commands is only *4 characters
wide*. This is enough for all the commands in japanese, but obviously not
in english. Magic, Fight, Terrain...none fit, without abbreviation or
squishing into less characters by making tiles for each. but, there is a
very small limit on how many tiles we have to make those with.
It's VERY hard.