Games like The Janus Problem
Games like The Janus Problem include Portal, Portal 2, The Talos Principle 2, The Entropy Centre, and The Ball. We matched them by the tags players give The Janus Problem on Steam (First-Person, Puzzle, Time Manipulation, Sci-fi, and Difficult): closest matches first, and among equally close ones the better-known games.

Portal
Shared: Puzzle · First-Person · Sci-fi

Portal 2
Shared: Puzzle · First-Person · Puzzle Platformer

The Talos Principle 2
Shared: Puzzle · First-Person · Sci-fi

The Entropy Centre
Shared: First-Person · Puzzle · Sci-fi

The Ball
Shared: First-Person · Puzzle · 3D Platformer

Quantum Conundrum
Shared: Puzzle · First-Person · Puzzle Platformer

The Talos Principle
Shared: Puzzle · First-Person · Sci-fi

SUPERHOT
Shared: Time Manipulation · First-Person · Puzzle

Viewfinder
Shared: Puzzle · First-Person · Puzzle Platformer

Hardspace: Shipbreaker
Shared: Sci-fi · Puzzle · First-Person

Baba Is You
Shared: Puzzle · Difficult · Logic

Supraland
Shared: First-Person · Puzzle · Puzzle Platformer

Braid
Shared: Puzzle · Time Manipulation · Puzzle Platformer

Lightmatter
Shared: Puzzle · First-Person · Logic

Buckshot Roulette
Shared: First-Person · 3D · Puzzle

Antichamber
Shared: First-Person · Puzzle · Difficult

Hello Neighbor
Shared: First-Person · Difficult · 3D Platformer

The Witness
Shared: Puzzle · First-Person · Difficult

Superliminal
Shared: First-Person · Puzzle · Physics

Q.U.B.E: Director's Cut
Shared: Puzzle · First-Person · Sci-fi

Polarity
Shared: First-Person · Puzzle · Sci-fi

A Story About My Uncle
Shared: First-Person · Puzzle · 3D Platformer

The Turing Test
Shared: Puzzle · First-Person · Sci-fi

Ghostrunner
Shared: First-Person · Difficult · Sci-fi