Games like Tether
Games like Tether include Getting Over It with Bennett Foddy, A Difficult Game About Climbing, Geometry Dash, Hollow Knight, and Jump King. We matched them by the tags players give Tether on Steam (Platformer, Physics, Funny, Difficult, and Action): closest matches first, and among equally close ones the better-known games.

Getting Over It with Bennett Foddy
Shared: Physics · Difficult · Singleplayer

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

Geometry Dash
Shared: Difficult · Platformer · 2D

Hollow Knight
Shared: Platformer · Difficult · 2D

Jump King
Shared: Difficult · Platformer · Psychological Horror

Celeste
Shared: Difficult · Platformer · Singleplayer

Pogostuck: Rage With Your Friends
Shared: Difficult · Platformer · Psychological Horror

Gang Beasts
Shared: Funny · Physics · Action

Pizza Tower
Shared: Platformer · Funny · Singleplayer

Super Meat Boy
Shared: Platformer · Difficult · 2D

Hollow Knight: Silksong
Shared: Difficult · Platformer · Singleplayer

BEEP
Shared: Platformer · Physics · Singleplayer

Cuphead
Shared: Platformer · Difficult · 2D

Human Fall Flat
Shared: Funny · Physics · Adventure

Garry's Mod
Shared: Physics · Funny · Singleplayer

Portal 2
Shared: Platformer · Singleplayer · Funny

Grand Theft Auto V Legacy
Shared: Action · Multiplayer · Singleplayer

SANABI
Shared: Action · Singleplayer · Platformer

People Playground
Shared: Physics · Singleplayer · 2D

I wanna be the Creator
Shared: Platformer · Action · Difficult

SpeedRunners
Shared: Platformer · Action · Multiplayer

Trials Fusion™
Shared: Physics · Platformer · Singleplayer

Clustertruck
Shared: Action · Physics · Singleplayer

Chained Together
Shared: Platformer · Funny · Adventure