Games like Not So Heart
Games like Not So Heart include Super Meat Boy, Celeste, Geometry Dash, VVVVVV, and Jump King. We matched them by the tags players give Not So Heart on Steam (Precision Platformer, Difficult, Psychedelic, Surreal, and Cats): closest matches first, and among equally close ones the better-known games.

Super Meat Boy
Shared: Precision Platformer · Difficult · Platformer

Celeste
Shared: Precision Platformer · Difficult · Pixel Graphics

Geometry Dash
Shared: Difficult · Precision Platformer · Colorful

VVVVVV
Shared: Precision Platformer · Difficult · Pixel Graphics

Jump King
Shared: Difficult · Precision Platformer · Pixel Graphics

Downwell
Shared: Precision Platformer · Difficult · Pixel Graphics

Alex Kidd in Miracle World DX
Shared: Precision Platformer · Difficult · Colorful

SANABI
Shared: Pixel Graphics · 2D Platformer · Difficult

Hotline Miami
Shared: Pixel Graphics · Psychedelic · Difficult

Shovel Knight: Treasure Trove
Shared: Retro · Difficult · Pixel Graphics

Post Void
Shared: Psychedelic · Difficult · Surreal

Dungeon Escape
Shared: Precision Platformer · Difficult · Retro

Pizza Tower
Shared: 2D Platformer · Pixel Graphics · Platformer

Ambidextro
Shared: Precision Platformer · Pixel Graphics · 2D Platformer

Katana ZERO
Shared: Pixel Graphics · Platformer · 2D Platformer

The End Is Nigh
Shared: Precision Platformer · Difficult · Platformer

A Dance of Fire and Ice
Shared: Difficult · Psychedelic · Colorful

The Messenger
Shared: Retro · Pixel Graphics · Platformer

Super Meat Boy Forever
Shared: Difficult · Precision Platformer · Platformer

Garbanzo Quest
Shared: Precision Platformer · Pixel Graphics · 2D Platformer

Cuphead
Shared: Difficult · Platformer · Retro

Kaze and the Wild Masks
Shared: Precision Platformer · Old School · Difficult

PUSS!
Shared: Difficult · Psychedelic · Cats

Hollow Knight
Shared: Difficult · Platformer · Indie