Games like My Koi
Games like My Koi include Mountain, DrainSim, ABZU, Ballads of Hongye: REBORN, and PC Building Simulator. We matched them by the tags players give My Koi on Steam (Relaxing, Simulation, Nature, Beautiful, and Underwater): closest matches first, and among equally close ones the better-known games.

Mountain
Shared: Simulation · Relaxing · Casual

DrainSim
Shared: Simulation · Relaxing · Casual

ABZU
Shared: Relaxing · Underwater · Atmospheric

Ballads of Hongye: REBORN
Shared: Simulation · Relaxing · Casual

PC Building Simulator
Shared: Simulation · Immersive Sim · Relaxing

Equilinox
Shared: Simulation · Relaxing · Casual

Ultimate Fishing Simulator
Shared: Simulation · Nature · 3D

PowerWash Simulator
Shared: Relaxing · Simulation · Casual

Euro Truck Simulator 2
Shared: Simulation · Relaxing · Realistic

Placid Plastic Duck Simulator
Shared: Relaxing · Casual · Simulation

American Truck Simulator
Shared: Simulation · Relaxing · Realistic

The Sims™ 4
Shared: Simulation · Relaxing · Life Sim

Librarian: Tidy Up the Arcane Library!
Shared: Relaxing · Simulation · Casual

House Flipper
Shared: Simulation · Relaxing · Casual

Unpacking
Shared: Relaxing · Casual · Simulation

Stardew Valley
Shared: Relaxing · Simulation · Life Sim

Crime Scene Cleaner
Shared: Simulation · Relaxing · Atmospheric

Train Simulator Classic
Shared: Simulation · Relaxing · Realistic

Cloud Gardens
Shared: Nature · Relaxing · Atmospheric

Jalopy
Shared: Relaxing · Nature · Simulation

Farming Simulator 25
Shared: Simulation · Realistic · 3D

Journey
Shared: Beautiful · Relaxing · Atmospheric

Electrician Simulator
Shared: Simulation · Immersive Sim · Relaxing

Retro Rewind - Video Store Simulator
Shared: Simulation · Relaxing · Casual