Games like The Crimson Diamond
Games like The Crimson Diamond include Papers, Please, The Rewinder, Strange Horticulture, The Case of the Golden Idol, and Kathy Rain. We matched them by the tags players give The Crimson Diamond on Steam (Mystery, Retro, Cozy, Old School, and Pixel Graphics): closest matches first, and among equally close ones the better-known games.

Papers, Please
Shared: Pixel Graphics · Point & Click · Retro

The Rewinder
Shared: Mystery · Pixel Graphics · Point & Click

Strange Horticulture
Shared: Mystery · Cozy · Point & Click

The Case of the Golden Idol
Shared: Mystery · Point & Click · 2D

Kathy Rain
Shared: Mystery · Point & Click · Pixel Graphics

No Case Should Remain Unsolved
Shared: Point & Click · Pixel Graphics · Female Protagonist

The Darkside Detective
Shared: Mystery · Point & Click · Pixel Graphics

Urban Myth Dissolution Center
Shared: Mystery · Pixel Graphics · 2D

The Blackwell Legacy
Shared: Mystery · Point & Click · Pixel Graphics

Your Turn To Die -Death Game By Majority-
Shared: Mystery · Female Protagonist · Point & Click

Whispers of a Machine
Shared: Point & Click · Pixel Graphics · Mystery

Shovel Knight: Treasure Trove
Shared: Retro · Pixel Graphics · 2D

Thimbleweed Park™
Shared: Pixel Graphics · Point & Click · Retro

The Excavation of Hob's Barrow
Shared: Point & Click · Pixel Graphics · Mystery

Void Stranger
Shared: Mystery · Pixel Graphics · Singleplayer

Broken Sword 2 - the Smoking Mirror: Remastered (2010)
Shared: Mystery · Retro · Point & Click

Unavowed
Shared: Point & Click · Mystery · Pixel Graphics

The Roottrees are Dead
Shared: Mystery · Point & Click · Singleplayer

Pentiment
Shared: Mystery · Historical · Adventure

Firework
Shared: Mystery · 2D · Old School

Return of the Obra Dinn
Shared: Mystery · Singleplayer · Retro

NORCO
Shared: Mystery · Point & Click · Pixel Graphics

Ten Trials of Babel: The Doppelganger Maze
Shared: Pixel Graphics · Female Protagonist · Mystery

The Drifter
Shared: Mystery · Pixel Graphics · Point & Click