Games like Terra Toy
Games like Terra Toy include Townscaper, SUMMERHOUSE, Town to City, Cities: Skylines II, and Tiny Glade. We matched them by the tags players give Terra Toy on Steam (Sandbox, Relaxing, Building, Singleplayer, and City Builder): closest matches first, and among equally close ones the better-known games.

Townscaper
Shared: Relaxing · Sandbox · Building

SUMMERHOUSE
Shared: Sandbox · Relaxing · Singleplayer

Town to City
Shared: Building · City Builder · Relaxing

Cities: Skylines II
Shared: Sandbox · Building · City Builder

Tiny Glade
Shared: Relaxing · Building · Sandbox

My Dream Setup
Shared: Relaxing · Building · Sandbox

Planet Coaster
Shared: Building · Sandbox · Relaxing

Gourdlets
Shared: Sandbox · Relaxing · City Builder

Cities: Skylines
Shared: Building · City Builder · Sandbox

House Flipper
Shared: Singleplayer · Building · Relaxing

Paralives
Shared: Building · Sandbox · Indie

ISLANDERS
Shared: Relaxing · Building · City Builder

Hozy
Shared: Relaxing · Sandbox · Cozy

Slime Rancher 2
Shared: Relaxing · Singleplayer · Cute

Garry's Mod
Shared: Sandbox · Building · Singleplayer

Foundation
Shared: Sandbox · City Builder · Building

Space Engineers
Shared: Sandbox · Building · Singleplayer

Stardew Valley
Shared: Relaxing · Sandbox · Building

Banished
Shared: City Builder · Sandbox · Singleplayer

The Sims™ 4
Shared: Building · Sandbox · Singleplayer

Planet Coaster 2
Shared: Sandbox · Building · City Builder

Kerbal Space Program
Shared: Sandbox · Building · Space

Planet Zoo
Shared: Sandbox · Building · City Builder

Jurassic World Evolution
Shared: Building · Sandbox · Singleplayer