Games like Slime Jump
Games like Slime Jump include Celeste, Geometry Dash, Only Climb: Better Together, Jump King, and Super Meat Boy. We matched them by the tags players give Slime Jump on Steam (Precision Platformer, 3D Platformer, Difficult, Platformer, and Arcade): closest matches first, and among equally close ones the better-known games.

Celeste
Shared: Precision Platformer · Difficult · Platformer

Geometry Dash
Shared: Difficult · Precision Platformer · Platformer

Only Climb: Better Together
Shared: Precision Platformer · 3D Platformer · Difficult

Jump King
Shared: Precision Platformer · Difficult · Psychological Horror

Super Meat Boy
Shared: Precision Platformer · Difficult · Platformer

Downwell
Shared: Precision Platformer · Platformer · Arcade

VVVVVV
Shared: Precision Platformer · Platformer · Difficult

Lunistice
Shared: 3D Platformer · Platformer · Cute

Pogostuck: Rage With Your Friends
Shared: Precision Platformer · Difficult · Platformer

Hollow Knight
Shared: Platformer · Difficult · Indie

Toree 3D
Shared: 3D Platformer · Platformer · Precision Platformer

The End Is Nigh
Shared: Precision Platformer · Platformer · Difficult

Get To Work
Shared: Difficult · Precision Platformer · 3D Platformer

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

Crash Bandicoot™ N. Sane Trilogy
Shared: 3D Platformer · Platformer · Difficult

Changed
Shared: Difficult · Cute · Psychological Horror

Getting Over It with Bennett Foddy
Shared: Difficult · Psychological Horror · Platformer

A Difficult Game About Climbing
Shared: Difficult · Precision Platformer · Platformer

Rain World
Shared: Difficult · Platformer · Pixel Graphics

PAC-MAN WORLD Re-PAC
Shared: 3D Platformer · 3D · Arcade

A Hat in Time
Shared: 3D Platformer · Cute · Platformer

Hollow Knight: Silksong
Shared: Difficult · Platformer · Indie

ATLYSS
Shared: Character Customization · 3D Platformer · Cute

Sonic Adventure DX
Shared: 3D Platformer · Platformer · Adventure