Games like Detective Agency
Games like Detective Agency include Storyteller, There Is No Game: Wrong Dimension, The Room, Morphopolis, and Hidden Folks. We matched them by the tags players give Detective Agency on Steam (Adventure, Casual, Action-Adventure, Interactive Fiction, and Point & Click): closest matches first, and among equally close ones the better-known games.

Storyteller
Shared: Adventure · Interactive Fiction · Point & Click

There Is No Game: Wrong Dimension
Shared: Adventure · Point & Click · Puzzle

The Room
Shared: Adventure · Puzzle · Point & Click

Morphopolis
Shared: Casual · Adventure · Puzzle

Hidden Folks
Shared: Casual · Hidden Object · Point & Click

Return to Monkey Island
Shared: Adventure · Point & Click · Puzzle

Enigmatis: The Ghosts of Maple Creek
Shared: Adventure · Casual · Point & Click

Machinarium
Shared: Point & Click · Puzzle · Adventure

Hidden Through Time
Shared: Casual · Hidden Object · Point & Click

Puzzle Agent
Shared: Casual · Point & Click · Puzzle

Gorogoa
Shared: Puzzle · Casual · Point & Click

The Room 4: Old Sins
Shared: Adventure · Puzzle · Point & Click

My Brother Rabbit
Shared: Adventure · Point & Click · Puzzle

Old Man's Journey
Shared: Adventure · Casual · Puzzle

The Room Two
Shared: Puzzle · Point & Click · Adventure

Scribblenauts Unlimited
Shared: Casual · Adventure · Puzzle

Enigmatis 3: The Shadow of Karkhala
Shared: Casual · Adventure · Hidden Object

Enigmatis 2: The Mists of Ravenwood
Shared: Adventure · Casual · Hidden Object

Neighbours back From Hell
Shared: Point & Click · Adventure · Puzzle

12 Labours of Hercules
Shared: Casual · Adventure · Time Management

Grim Legends: The Forsaken Bride
Shared: Casual · Adventure · Point & Click

Grim Legends 2: Song of the Dark Swan
Shared: Casual · Adventure · Hidden Object

Unforeseen Incidents
Shared: Adventure · Point & Click · Puzzle

No Case Should Remain Unsolved
Shared: Interactive Fiction · Puzzle · Adventure