Partial conversion mods — these mods retain most of the existing assets, but gain new units, factions and sometimes mechanics.
Total conversion mods — the entire game theme is overhauled, factions and units are most often completely different than found in the game that is modified or the majority of their assets have been replaced or redone. Game mechanics are often added or expanded.
Graphics mods — these mods only alter the graphical appearance of selected elements of the game. They are often compatible with users who do not have them.
Unofficial patches — often done in the form of a mod, these projects do not add new assets to the game, and instead tend to fix many of the bugs left over after the original game's support ended. Some of them also change the balance to improve the game experience.
The original Red Alert, Tiberian Sun, and Red Alert 2 utilize several INI configuration files that can be edited to modify the behavior of objects in-game. There are primarily three types of files in these games:
art.ini — the configuration file for art and graphics
ai.ini — the configuration file for the computer AI to define which units it will use
rules.ini — the main configuration file for all in-game logic and behavior, e.g. unit stats
There are two types of art files for Tiberian Sun and Red Alert 2:
SHP: These files are 2D animated images (much like GIF files) but require palettes for use. They are mainly used for buildings, infantry and landscape tiles.
VXL (voxel files) and HVA: These two types of files work in unison with each other. The VXL contains the main 3D art, whilst the HVA contains information on use for the game, i.e. rotor blades etc.