Games like CITADEL
Games like CITADEL include Until Then, Milk outside a bag of milk outside a bag of milk, STEINS;GATE, Undertale, and The Red Strings Club. We matched them by the tags players give CITADEL on Steam (Visual Novel, Philosophical, Sci-fi, Story Rich, and Choices Matter): closest matches first, and among equally close ones the better-known games.

Until Then
Shared: Visual Novel · Story Rich · Pixel Graphics

Milk outside a bag of milk outside a bag of milk
Shared: Visual Novel · Story Rich · Pixel Graphics

STEINS;GATE
Shared: Visual Novel · Story Rich · Sci-fi

Undertale
Shared: Story Rich · Choices Matter · Pixel Graphics

The Red Strings Club
Shared: Story Rich · Pixel Graphics · Choices Matter

Zero Escape: The Nonary Games
Shared: Visual Novel · Story Rich · Choices Matter

OneShot
Shared: Story Rich · Pixel Graphics · Choices Matter

Detroit: Become Human
Shared: Story Rich · Choices Matter · Sci-fi

The Test
Shared: Story Rich · Pixel Graphics · Visual Novel

Milk inside a bag of milk inside a bag of milk
Shared: Visual Novel · Philosophical · Interactive Fiction

Coffee Talk
Shared: Visual Novel · Pixel Graphics · Story Rich

Roadwarden
Shared: Pixel Graphics · Story Rich · Adventure

AI: The Somnium Files
Shared: Visual Novel · Story Rich · Mystery

Suzerain
Shared: Visual Novel · Choices Matter · Story Rich

The Wolf Among Us
Shared: Story Rich · Visual Novel · Choices Matter

STEINS;GATE 0
Shared: Visual Novel · Story Rich · Sci-fi

Lay a Beauty to Rest: The Darkness Peach Blossom Spring
Shared: Visual Novel · Mystery · Adventure

Refind Self: The Personality Test Game
Shared: Visual Novel · Story Rich · Interactive Fiction

The Life and Suffering of Sir Brante
Shared: Story Rich · Choices Matter · Visual Novel

Urban Myth Dissolution Center
Shared: Visual Novel · Pixel Graphics · Mystery

The Talos Principle
Shared: Philosophical · Sci-fi · Story Rich

The Hungry Lamb: Traveling in the Late Ming Dynasty
Shared: Visual Novel · Story Rich · Interactive Fiction

Tiny Bunny
Shared: Visual Novel · Story Rich · Choices Matter

NEEDY STREAMER OVERLOAD
Shared: Visual Novel · Pixel Graphics · Story Rich