The most popular mods are those developed for First Person Shooters, like Battlefield, Quake, Unreal Tournament and Half Life especially. Strategy games like Total Real Time Anihilation, Starcraft Broodwar, Warcraft III or Command Conquer also enjoy various communities. Keep in mind that while the programs used to create mods may be formal, modders (people who create mods) are mostly fans always wanting to dig deeper into their favorite games. People with much imagination and creativity are encouraged to the game. For these reasons, many mods are unfinished, and many have poor quality. In many cases the mods are created as “training” to learn how to use this or that tool, in other cases there is interest from the community, and in other cases personal problems, then extend the project for many months, the the creator’s own lack of interest makes the project remains unfinished.For reasons of copyright and its unofficial nature, requires that the mods are always free distribution.