so i installed lots of PK3 and WAD files for doom and doom 2, but this one... i didn't download it, i just found it laying on my gzdoom folder, so i played it... and wow, it's huge, it has 32 ENORMOUS levels, it's own titlescreen, and the icon of sin wall texture is replaced by a realistic human skull with horns, the fight isn't that different tough, anyways, i'm still confused, you can play it here https://drive.google.com/file/d/1To0xx-5Hn2K96bTuuDcckH0ONYRuxKlL/view?usp=sharing