Games like Attic
Games like Attic include The Henry Stickmin Collection, The Test, Undertale, Reventure, and The Stanley Parable. We matched them by the tags players give Attic on Steam (Choose Your Own Adventure, Adventure, Walking Simulator, Funny, and Pixel Graphics): closest matches first, and among equally close ones the better-known games.

The Henry Stickmin Collection
Shared: Choose Your Own Adventure · Funny · Multiple Endings

The Test
Shared: Choose Your Own Adventure · Pixel Graphics · Multiple Endings

Undertale
Shared: Pixel Graphics · Funny · Multiple Endings

Reventure
Shared: Adventure · Pixel Graphics · Multiple Endings

The Stanley Parable
Shared: Walking Simulator · Funny · Adventure

Firewatch
Shared: Adventure · Walking Simulator · Singleplayer

The Wolf Among Us
Shared: Adventure · Choose Your Own Adventure · Multiple Endings

DAVE THE DIVER
Shared: Adventure · Pixel Graphics · Singleplayer

Five Nights at Freddy's: Into the Pit
Shared: Adventure · Pixel Graphics · Singleplayer

While We Wait Here
Shared: Choose Your Own Adventure · Walking Simulator · Multiple Endings

Dungeon Munchies
Shared: Adventure · Pixel Graphics · Funny

Tales from the Borderlands
Shared: Adventure · Choose Your Own Adventure · Singleplayer

Finding Paradise
Shared: Adventure · Pixel Graphics · Funny

To the Moon
Shared: Adventure · Pixel Graphics · Singleplayer

There Is No Game: Wrong Dimension
Shared: Adventure · Pixel Graphics · Funny

Dead Cells
Shared: Adventure · Pixel Graphics · Singleplayer

Kindergarten
Shared: Funny · Pixel Graphics · Adventure

Hero's Adventure: Road to Passion
Shared: Multiple Endings · Adventure · Pixel Graphics

Ten Trials of Babel: The Doppelganger Maze
Shared: Pixel Graphics · Choose Your Own Adventure · Multiple Endings

Kindergarten 2
Shared: Adventure · Funny · Pixel Graphics

Slime Rancher
Shared: Adventure · Singleplayer · Funny

SANABI
Shared: Pixel Graphics · Adventure · Singleplayer

tERRORbane
Shared: Adventure · Choose Your Own Adventure · Multiple Endings

McPixel 3
Shared: Adventure · Pixel Graphics · Funny