Games like Ecto
Games like Ecto include Refunct, PEAK, Journey, Chained Together, and How to Fish. We matched them by the tags players give Ecto on Steam (Adventure, Casual, Parkour, Procedural Generation, and Nature): closest matches first, and among equally close ones the better-known games.

Refunct
Shared: Parkour · Casual · Relaxing

PEAK
Shared: Co-op · Adventure · Procedural Generation

Journey
Shared: Adventure · Co-op · Relaxing

Chained Together
Shared: Adventure · Co-op · Casual

How to Fish
Shared: Co-op · Adventure · FPS

Big Walk
Shared: Adventure · Casual · Exploration

A Story About My Uncle
Shared: Adventure · Parkour · Casual

A Short Hike
Shared: Adventure · Relaxing · Casual

Deep Rock Galactic
Shared: Co-op · Procedural Generation · FPS

RV There Yet?
Shared: Co-op · Adventure · Exploration

Flower
Shared: Casual · Adventure · Relaxing

ABZU
Shared: Adventure · Relaxing · Casual

Lethal Company
Shared: Co-op · Exploration · Procedural Generation

Far Cry® 5
Shared: Co-op · FPS · Adventure

Slime Rancher
Shared: Adventure · Exploration · Casual

theHunter: Call of the Wild™
Shared: Nature · FPS · Relaxing

Way of the Hunter
Shared: Adventure · FPS · Exploration

Bomb Rush Cyberfunk
Shared: Adventure · Parkour · 3D Platformer

Slime Rancher 2
Shared: Adventure · Relaxing · Casual

Echo Point Nova
Shared: FPS · Parkour · Adventure

DAVE THE DIVER
Shared: Adventure · Casual · Relaxing

No Man's Sky
Shared: Adventure · Procedural Generation · Exploration

AER Memories of Old
Shared: Adventure · Relaxing · Exploration

Fears to Fathom® - Scratch Creek
Shared: Co-op · Adventure · Casual