A Plain-English Glossary of Pokemon ROM Hack Terms
ROM hack release notes assume a vocabulary most players never had to learn. Here is the whole set, in plain words, so a readme stops being a wall of jargon.
The files
Patch
A small file of instructions that turns a clean ROM into the hacked game. Legal to share. If you only download one file, it is this.
Base ROM
The original game a hack is built on, most often FireRed for GBA hacks. You patch onto the base. A FireRed hack will not patch onto Emerald.
Patched ROM
The output you actually play. You make it once from the patch and the base, then keep it.
Emulator
The app that runs the patched ROM. mGBA for GBA, Mesen for SNES, and Delta for phones are the safe picks.
The playstyle words
Nuzlocke
A self-imposed ruleset: faint a Pokemon and release it, catch only the first encounter per route. A hack marked Nuzlocke-ready means it survives this.
Hard mode
Trainers have smarter AI, higher levels, and better moves. It does not change the story, only how much it punishes you.
EVs and IVs
Hidden stats. EVs you earn by battling, IVs are set per Pokemon. A hack with EV/IV display just lets you see them on the summary screen.
Mega evolution
A mid-battle one-form change from later generations, back-ported into GBA hacks. Temporary and powerful.
Half the replies asking for help were just people who did not know what a base ROM was. Pinning a glossary would have saved us a week.
Frequently asked questions
What is the difference between a ROM and a patch
The ROM is the whole game. The patch is only the changes. Sharing the patch is fine; sharing the ROM is not. You combine a patch with your own ROM to play.
Do I need to know these terms to play
Only three: base ROM, patch, and emulator. The rest you learn if you pick up Nuzlocke or hard mode, which are optional.
What does difficulty meant for Nuzlocke mean
The hack is balanced so that playing with Nuzlocke rules, where a fainted Pokemon is released, is survivable. A normal hack balanced for Nuzlocke would be too easy without those rules.
Is megas in this hack a good sign
It means the hack pulled a feature from later generations into an older engine. It usually signals an ambitious, lovingly made hack, not a warning.