A lot of games are also based on long community traditions of modification too. Popular games like League of Legends and Dota2 for instance are based on a mod called Dota Allstars which is itself an amalgamation of other popular Warcraft 3 mods along with solicited direct incorporation of player suggestions then of course the base game of warcraft itself is a rip off of warhammer and it goes on. The ability to modify these games is often an encouraged and developer supported core feature of the games.