Games like Illusoria
Games like Illusoria include Hollow Knight, Touhou Luna Nights, Hollow Knight: Silksong, SANABI, and Ori and the Will of the Wisps. We matched them by the tags players give Illusoria on Steam (Exploration, Side Scroller, Puzzle, Difficult, and Platformer): closest matches first, and among equally close ones the better-known games.
Hollow Knight
Shared: Platformer · Difficult · Exploration
Touhou Luna Nights
Shared: Side Scroller · Difficult · Exploration
Hollow Knight: Silksong
Shared: Difficult · Exploration · Platformer
SANABI
Shared: Story Rich · Action · Platformer
Ori and the Will of the Wisps
Shared: Platformer · Exploration · Action
Rogue Legacy 2
Shared: Arcade · Platformer · Difficult
STAR WARS Jedi: Fallen Order™
Shared: Action-Adventure · Exploration · Platformer
Celeste
Shared: Difficult · Platformer · Pixel Graphics
Rain World
Shared: Exploration · Difficult · Platformer
Skul: The Hero Slayer
Shared: Platformer · Action · 2D
ANIMAL WELL
Shared: Exploration · Puzzle · Platformer
LIMBO
Shared: Puzzle · Platformer · 2D
Bloodstained: Ritual of the Night
Shared: Side Scroller · RPG · Platformer
Portal 2
Shared: Puzzle · Platformer · Story Rich
Geometry Dash
Shared: Difficult · Platformer · 2D
Tomb Raider Game of the Year
Shared: Exploration · Action · Story Rich
Dungeon Munchies
Shared: Exploration · RPG · Action
Shovel Knight: Treasure Trove
Shared: Platformer · Difficult · Side Scroller
La-Mulana
Shared: Difficult · Exploration · Platformer
Rise of the Tomb Raider™
Shared: Exploration · Action · Action-Adventure
Dust: An Elysian Tail
Shared: Platformer · RPG · Action
Rabi-Ribi
Shared: Exploration · Side Scroller · Anime
Afterimage
Shared: Side Scroller · Exploration · Difficult
FEZ
Shared: Puzzle · Exploration · Platformer