Well from what I understand you want to make a MMORPG; that's pretty much impossible to do by hacking, so your next option is Game Development. There, you make games from scratch using programs like RPG Maker XP and so on. Very different to ROM Hacking.
You should make sure to check sticky threads in the sections you visit to get an understanding of how things work there. ;)
You should make sure to check sticky threads in the sections you visit to get an understanding of how things work there. ;)