SlackBuildsOrg/games/heretic_shareware_data

Game data from the shareware release of Heretic (heretic1.wad, v1.2). 
Includes only the first episode of the game.

You'll need a Doom engine that's capable of playing Heretic to use this.
zdoom will work; prboom, prboom-plus, odamex, and skulltag won't.