This..Is The DoomsDay Disk, A 1995 CD-Rom from Multi Media Machine Limited, It contains 1800 levels split between Doom, Doom II, Heretic, Star Wars Dark Forces and Descent, It also has a goodies folder of sound and texture editors, hints/cheats, and Level editors. This file was originally on Archive.org and I do not own it nor do I take credit for the file either.