The phrase "nightmarish world" refers to a situation or place that can cause intense fear or anxiety, similar to a bad dream or nightmare. It suggests a frightening or unpleasant reality. Full definition
Nintendo's vibrantly colourful and rather unconventional entry into the world of competitive multiplayer shooters with Splatoon was third, juxtaposed with the muted tones and nightmarish world in the brutally difficult Bloodborne in second. (thesixthaxis.com)
But when Vincent meets Catherine he wakes up in a whole new world and has to fight his way through nightmarish worlds to find his way back to the life he wants to have. (gamergeddon.com)
Everyone is scared of what people think of them and hides in his own little nightmarish world. (nakedpastor.com)