Games like Still, I am.
Games like Still, I am. include Portal 2, Portal, INSIDE, LIMBO, and The Last Campfire. We matched them by the tags players give Still, I am. on Steam (3D Platformer, Puzzle Platformer, Puzzle, Platformer, and 2.5D): closest matches first, and among equally close ones the better-known games.

Portal 2
Shared: Puzzle · Platformer · Puzzle Platformer

Portal
Shared: Puzzle Platformer · Puzzle · 3D Platformer

INSIDE
Shared: Puzzle Platformer · 2.5D · Puzzle

LIMBO
Shared: Puzzle Platformer · Puzzle · Platformer

The Last Campfire
Shared: Puzzle · Cute · 3D Platformer

Little Nightmares
Shared: Puzzle Platformer · Puzzle · Adventure

Papo & Yo
Shared: 3D Platformer · Puzzle Platformer · Puzzle

The Pedestrian
Shared: Puzzle Platformer · Puzzle · Platformer

Tinykin
Shared: 3D Platformer · Puzzle · Cute

Viewfinder
Shared: Puzzle Platformer · Puzzle · Surreal

Chained Together
Shared: Platformer · Puzzle Platformer · 3D Platformer

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

FAR: Changing Tides
Shared: Puzzle Platformer · 2.5D · Platformer

The Talos Principle 2
Shared: Puzzle · Puzzle Platformer · 3D Platformer

FEZ
Shared: Puzzle · Platformer · Puzzle Platformer

Shady Part of Me
Shared: Puzzle · Platformer · 3D Platformer

ANIMAL WELL
Shared: Puzzle · Puzzle Platformer · Platformer

Seen
Shared: Puzzle · Platformer · Puzzle Platformer

FAR: Lone Sails
Shared: 2.5D · Puzzle · Puzzle Platformer

It Takes Two
Shared: Puzzle · Puzzle Platformer · 3D Platformer

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

Arise: A Simple Story
Shared: 3D Platformer · Puzzle Platformer · Cute

Trine 3: The Artifacts of Power
Shared: Puzzle Platformer · 3D Platformer · Puzzle

Moss: The Forgotten Relic
Shared: 3D Platformer · Puzzle Platformer · Puzzle