Doom is a classic FPS game developed by Id Software in 1993. Ultimate Doom is newer version with additional episode and introducing Nightmare! difficulty. In 1997 Id Software published Doom engine source code under GNU GPL license. Based on published source code was made many different Doom engines for different platforms known as source ports. I use GZDoom source port to take advantage of fixed bugs, jump ability and mouse freelook. However I play all the maps as intended (I mean I don't use jumps to bypass a moats, and I try to kill all enemies and get all items). My goal was to get 100% secrets on Ultra-Violence difficulty.