Hello
and welcome to the place of evil, where all of my doom wads are. be sure to try them out !!
What the hell is .wad ?
.wad is format for doom maps that quake also used, they are really simple to store info about map,enemies and pickups
But how to run .wad ?
For that you need GZDOOM, wich allows you to run .wad files. I would recommend visiting Doom Wiki for more information