Games like Harpy
Games like Harpy include Downwell, Celeste, Super Meat Boy, SANABI, and VVVVVV. We matched them by the tags players give Harpy on Steam (Action, Casual, Arcade, Platformer, and 2D Platformer): closest matches first, and among equally close ones the better-known games.

Downwell
Shared: Precision Platformer · Platformer · Arcade

Celeste
Shared: Precision Platformer · Platformer · 2D Platformer

Super Meat Boy
Shared: Platformer · Precision Platformer · 2D Platformer

SANABI
Shared: Action · 2D Platformer · Pixel Graphics

VVVVVV
Shared: Platformer · Precision Platformer · 2D Platformer

Sonic Origins
Shared: Action · 2D Platformer · Platformer

Katana ZERO
Shared: Action · Platformer · Pixel Graphics

Webbed
Shared: 2D Platformer · Exploration · Platformer

Rain World
Shared: Exploration · Platformer · Atmospheric

Broforce
Shared: Action · Platformer · Pixel Graphics

Hollow Knight
Shared: Platformer · 2D · Exploration

UFO 50
Shared: Action · Arcade · Pixel Graphics

Twin Shot Deluxe
Shared: Action · Casual · Arcade

Vampire Survivors
Shared: Casual · Pixel Graphics · 2D

Shovel Knight: Treasure Trove
Shared: Platformer · Action · Pixel Graphics

Timberman
Shared: Casual · Action · Arcade

FEZ
Shared: Platformer · Exploration · Casual

Jump King
Shared: Precision Platformer · Action · Platformer

Pizza Tower
Shared: 2D Platformer · Platformer · Action

Ambidextro
Shared: Action · 2D Platformer · Precision Platformer

Superflight
Shared: Casual · Action · Indie

Skul: The Hero Slayer
Shared: Action · Platformer · Pixel Graphics

Brawlhalla
Shared: Casual · 2D Platformer · Platformer

Rogue Legacy
Shared: Platformer · Action · 2D