The point of Crispy is to be closer to vanilla than ports like GZDoom, Zandronum, PRBoom, etc, but still remove some static limits (that custom maps need to work) and increase the render resolution (which GZDoom etc do, but vanilla and ports like Chocolate Doom don't).

Basically it's Chocolate Doom (which is essentially 1994 Doom, but it builds and runs on modern systems), but a little more easy to use and a little more compatible.