Games like Slime's Journey
Games like Slime's Journey include Zup! S, Plants vs. Zombies GOTY Edition, Potion Craft: Alchemist Simulator, Celeste, and Webbed. We matched them by the tags players give Slime's Journey on Steam (Casual, Strategy, Platformer, 2D Platformer, and 2D): closest matches first, and among equally close ones the better-known games.

Zup! S
Shared: Casual · 2D · Indie

Plants vs. Zombies GOTY Edition
Shared: Strategy · Casual · 2D

Potion Craft: Alchemist Simulator
Shared: Crafting · Relaxing · 2D

Celeste
Shared: Platformer · 2D Platformer · Indie

Webbed
Shared: 2D Platformer · Cute · Platformer

Game Dev Tycoon
Shared: Strategy · Casual · Indie

Shelldiver
Shared: Casual · 2D · Relaxing

Bloons TD 6
Shared: Strategy · Casual · Singleplayer

Unpacking
Shared: Casual · Cute · Relaxing

Braid
Shared: 2D Platformer · Platformer · 2D

Plague Inc: Evolved
Shared: Strategy · Casual · Indie

Zup!
Shared: Casual · 2D · Indie

A Game About Feeding A Black Hole
Shared: Casual · Strategy · Relaxing

Hollow Knight
Shared: Platformer · 2D · Indie

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

Mini Motorways
Shared: Strategy · Casual · Relaxing

Mini Metro
Shared: Strategy · Casual · Indie

BEEP
Shared: Platformer · 2D · Indie

Moonleap
Shared: Platformer · Strategy · Relaxing

Montaro
Shared: Casual · Cute · Platformer

A Little to the Left
Shared: Casual · Relaxing · Cute

Ballionaire
Shared: Casual · 2D · Strategy

Zup! 3
Shared: Casual · 2D · Indie

FEZ
Shared: Platformer · Casual · Indie