Games like Nightmare Boy
Games like Nightmare Boy include Hollow Knight, Hollow Knight: Silksong, Momodora: Reverie Under The Moonlight, Touhou Luna Nights, and Cave Story+. We matched them by the tags players give Nightmare Boy on Steam (Exploration, Metroidvania, Side Scroller, Difficult, and Platformer): closest matches first, and among equally close ones the better-known games.
Hollow Knight
Shared: Metroidvania · Platformer · Difficult
Hollow Knight: Silksong
Shared: Metroidvania · Difficult · Exploration
Momodora: Reverie Under The Moonlight
Shared: Metroidvania · Side Scroller · Exploration
Touhou Luna Nights
Shared: Metroidvania · Side Scroller · Difficult
Cave Story+
Shared: Exploration · Metroidvania · Difficult
Rain World
Shared: Exploration · Difficult · Platformer
Nine Sols
Shared: Metroidvania · Difficult · Platformer
Ori and the Will of the Wisps
Shared: Metroidvania · Platformer · Exploration
Gato Roboto
Shared: Metroidvania · 2D · Platformer
Blasphemous
Shared: Metroidvania · 2D · Difficult
Skul: The Hero Slayer
Shared: 2D · Metroidvania · Platformer
Rabi-Ribi
Shared: Metroidvania · Exploration · Side Scroller
ANIMAL WELL
Shared: Exploration · Metroidvania · Platformer
Monster Boy and the Cursed Kingdom
Shared: Metroidvania · Platformer · Exploration
La-Mulana
Shared: Metroidvania · Difficult · Exploration
Axiom Verge
Shared: Metroidvania · Platformer · 2D
Dust: An Elysian Tail
Shared: Metroidvania · Platformer · 2D
Cuphead
Shared: Difficult · Platformer · 2D
Rogue Legacy 2
Shared: Metroidvania · Platformer · Difficult
Bloodstained: Ritual of the Night
Shared: Metroidvania · Side Scroller · Platformer
Geometry Dash
Shared: Difficult · 2D · Platformer
Salt and Sanctuary
Shared: Metroidvania · Difficult · 2D
Guacamelee! 2
Shared: Metroidvania · Platformer · 2D
MIO: Memories in Orbit
Shared: Exploration · Metroidvania · Platformer