Games like GRR BOO I
Games like GRR BOO I include Celeste, Pizza Tower, SANABI, Hollow Knight, and Webbed. We matched them by the tags players give GRR BOO I on Steam (Adventure, Platformer, 2D Platformer, Action, and 2D): closest matches first, and among equally close ones the better-known games.

Celeste
Shared: Platformer · 2D Platformer · Adventure

Pizza Tower
Shared: 2D Platformer · Platformer · Action

SANABI
Shared: Action · Adventure · 2D Platformer

Hollow Knight
Shared: Platformer · 2D · Adventure

Webbed
Shared: 2D Platformer · Cute · Platformer

Ori and the Will of the Wisps
Shared: Platformer · Adventure · Action

Sonic Superstars
Shared: Platformer · Adventure · Action

Sonic the Hedgehog 4 Episode 1
Shared: Platformer · Adventure · Action

Sonic Origins
Shared: Adventure · 2D Platformer · Action

Monster Boy and the Cursed Kingdom
Shared: Adventure · Action · Platformer

Outcore: Desktop Adventure
Shared: Adventure · Comedy · Cute

Dust: An Elysian Tail
Shared: Platformer · Action · Adventure

Pikuniku
Shared: Adventure · Cute · Action

The Darkest Tales — Into the Nightmare
Shared: Adventure · Platformer · 2D Platformer

Rayman® Origins
Shared: Platformer · Adventure · 2D

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

Neva
Shared: Adventure · Platformer · 2D Platformer

SONIC X SHADOW GENERATIONS
Shared: Action · Platformer · Adventure

Trine 5: A Clockwork Conspiracy
Shared: Adventure · Action · Platformer

Katana ZERO
Shared: Action · Platformer · 2D Platformer

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

Shovel Knight: Treasure Trove
Shared: Platformer · Adventure · 2D

Janosik
Shared: Adventure · Platformer · Action

Sonic Mania
Shared: Platformer · 2D · Adventure