Games like Garden Guardian
Games like Garden Guardian include Muse Dash, SUPER CHICKEN JUMPER, Geometry Dash, A Dance of Fire and Ice, and Rift of the NecroDancer. We matched them by the tags players give Garden Guardian on Steam (Tutorial, Difficult, Arcade, Female Protagonist, and 2D): closest matches first, and among equally close ones the better-known games.

Muse Dash
Shared: Female Protagonist · Cute · Anime

SUPER CHICKEN JUMPER
Shared: Difficult · Arcade · 2D

Geometry Dash
Shared: Difficult · 2D · Arcade

A Dance of Fire and Ice
Shared: Difficult · Arcade · 2D

Rift of the NecroDancer
Shared: Difficult · Female Protagonist · Arcade

Hollow Knight: Silksong
Shared: Difficult · 2D · Female Protagonist

Hatsune Miku: Project DIVA Mega Mix+
Shared: Arcade · Cute · Female Protagonist

Pepper Grinder
Shared: Difficult · Arcade · Female Protagonist

Orbt XL
Shared: Difficult · Arcade · 2D

Celeste
Shared: Difficult · Female Protagonist · 2D

Little Witch Nobeta
Shared: Cute · Female Protagonist · Funny

Last Command
Shared: Difficult · 2D · Cute

Touhou Tenkuushou ~ Hidden Star in Four Seasons.
Shared: Difficult · Female Protagonist · Arcade

Super Hexagon
Shared: Difficult · Arcade · Indie

Touhou Koumakyou: New Classic - the Embodiment of Scarlet Devil
Shared: Difficult · Female Protagonist · 2D

DJMAX RESPECT V
Shared: Cute · 2D · Action

Shower With Your Dad Simulator 2015: Do You Still Shower With Your Dad
Shared: Arcade · 2D · Funny

Cat Goes Fishing
Shared: 2D · Cute · Funny

Zuma Deluxe
Shared: Arcade · 2D · Funny

ICEY
Shared: Female Protagonist · Action · Anime

Bit Blaster XL
Shared: Difficult · Arcade · 2D

Hollow Knight
Shared: Difficult · 2D · Indie

Giana Sisters: Twisted Dreams
Shared: Difficult · Arcade · Female Protagonist

Rogue Legacy 2
Shared: Arcade · Difficult · Action