Games like Fiend Heart
Games like Fiend Heart include Celeste, Pizza Tower, Zenless Zone Zero, SANABI, and Super Meat Boy. We matched them by the tags players give Fiend Heart on Steam (Difficult, 2D Platformer, Free to Play, Cute, and Funny): closest matches first, and among equally close ones the better-known games.

Celeste
Shared: Difficult · 2D Platformer · Singleplayer

Pizza Tower
Shared: 2D Platformer · Funny · Singleplayer

Zenless Zone Zero
Shared: Free to Play · Cute · Funny

SANABI
Shared: 2D Platformer · Action · Singleplayer

Super Meat Boy
Shared: Difficult · 2D Platformer · Singleplayer

Muse Dash
Shared: Cute · Singleplayer · Anime

Ultimate Custom Night
Shared: Free to Play · Difficult · Singleplayer

SUPER CHICKEN JUMPER
Shared: Difficult · Cute · Funny

Geometry Dash
Shared: Difficult · Singleplayer · 2D

Hollow Knight: Silksong
Shared: Difficult · Singleplayer · 2D

Momodora: Reverie Under The Moonlight
Shared: 2D Platformer · Side Scroller · Difficult

Hollow Knight
Shared: Difficult · Singleplayer · 2D

Little Witch Nobeta
Shared: Cute · Funny · Singleplayer

Thank Goodness You're Here!
Shared: Funny · 2D Platformer · Comedy

ICEY
Shared: Action · Side Scroller · Singleplayer

Dungeon Munchies
Shared: Funny · Action · Singleplayer

Getting Over It with Bennett Foddy
Shared: Difficult · Singleplayer · Funny

Eryi's Action
Shared: 2D Platformer · Difficult · Singleplayer

Will You Snail?
Shared: Difficult · 2D Platformer · Funny

Changed
Shared: Difficult · Cute · Singleplayer

Momoka (wo) Wasshoi
Shared: 2D Platformer · Cute · Funny

Skul: The Hero Slayer
Shared: Action · Difficult · Singleplayer

Afterimage
Shared: 2D Platformer · Side Scroller · Difficult

Outcore: Desktop Adventure
Shared: Free to Play · Cute · Singleplayer