Rules.ini

Rules.ini is a configuration file that included unit stats starting from Red Alert. It allows easy modifications because it was not hard-coded as in Tiberian Dawn. The rules.ini file as well as many other interesting files are located inside the game MIX files.
You can only access the files inside MIXs with XCC Mixer or MIX Editor.
==Accessing==
The location of Rules.ini depends on the game and/or expansion. You'll have to use XCC Utilities to open the MIXs and access the files. Rules.ini tends to be in a MIX inside the main MIX. Since the MIX files are encrypted, you can't use Notepad to access and extract the INIs, though the XCC Utilities have the key.
Rules.ini can be found here:
* RA1: RedAlert.mix > local.mix
* AM expansion: expand2.mix > aftrmath.ini (loaded after rules.ini and overrides/adds to RA1 rules)
* TS: TibSun.mix > local.mix (patch in expand01.mix)
* FS expansion: expand01.mix as firestrm.ini (loaded after rules.ini and overrides/adds to TibSun rules)
* RA2: RA2.mix > local.mix
* YR: RA2md.mix > localmd.mix > rulesmd.ini (unlike previous games does not override/add to rules.ini and is very much its own thing)
**YR patch in expandmd01.mix > rulesmd.ini
The only special program required to get access to rules.ini is XCC Mixer (alternatively use MIX Editor); use it to navigate to the file's location, extract it to somewhere where you have write permissions, then use Notepad, Notepad++ or your TXT editor of your choosing to edit the extracted INI.
Programs like TibEd or Red Alchemist do not load any custom INIs and instead load the one saved within their own files (the last patch's INIs), so modifying mods, even simple INI mods, is not possible. They are specialized in modifying these values in an annotated manner with selection boxes showing the allowed values to aid new modders.
These programs should not be used except to slowly get used to modding; after that text editors should be used.
Expansion packs used differently named files that served the same purpose, e.g. aftrmath.ini, firestrm.ini or rulesmd.ini.
As of Generals, a unique Rules file is no longer used. Instead, it is split into several parts.
==Usage==
Rules.ini manipulates unit/building stats, weapons, armour, mobility and similar attributes. However, unit/building appearances and all animations are handled by Art.ini.
==Annotated Rules.ini files==
* Tiberian Dawn ini rules, converted from the hardcoded exe data by Nyerguds
* Red Alert 2 INI files @ YR Arg
* Yuri's Revenge INI files @ YR Argentina