The first person shooter Doom launched in 1993 and quickly secured its place in popular culture. The game’s creators were unusually mod-friendly, and they set the game up so it was easy and legal for fans to create their own Doom level packs (known as WADs) and distribute them online. Players took full advantage of this aspect of the game, and BBSes were soon flooded with custom Doom levels.

27 years later, Doom still has a thriving modding community. We spoke with writer, musician, and game designer Liz Ryerson, who gave us her historical and critical perspective on player-created Doom maps.