Games like Sunny Reef
Games like Sunny Reef include Terraria, Stardew Valley, The Forest, Core Keeper, and Space Engineers. We matched them by the tags players give Sunny Reef on Steam (Exploration, Hidden Object, Sandbox, Survival, and Fishing): closest matches first, and among equally close ones the better-known games.

Terraria
Shared: Sandbox · Survival · Exploration

Stardew Valley
Shared: Farming Sim · Sandbox · Life Sim

The Forest
Shared: Survival · Exploration · Building

Core Keeper
Shared: Exploration · Survival · Sandbox

Space Engineers
Shared: Sandbox · Survival · Building

Rust
Shared: Survival · Sandbox · Building

Once Human
Shared: Survival · Exploration · Building

The Long Dark
Shared: Exploration · Survival · Sandbox

7 Days to Die
Shared: Survival · Exploration · Sandbox

My Time at Portia
Shared: Life Sim · Simulation · Farming Sim

Conan Exiles Enhanced
Shared: Survival · Building · Sandbox

Sons Of The Forest
Shared: Survival · Exploration · Building

Valheim
Shared: Survival · Exploration · Building

Scrap Mechanic
Shared: Sandbox · Survival · Building

No Man's Sky
Shared: Exploration · Survival · Sandbox

Farmer's Dynasty 2
Shared: Sandbox · Exploration · Simulation

Starbound
Shared: Sandbox · Survival · Exploration

Disney Dreamlight Valley
Shared: Exploration · Sandbox · Life Sim

Empyrion - Galactic Survival
Shared: Survival · Exploration · Simulation

Forager
Shared: Survival · Sandbox · Farming Sim

Don't Starve
Shared: Survival · Sandbox · Exploration

ASTRONEER
Shared: Exploration · Survival · Sandbox

TerraTech
Shared: Sandbox · Building · Survival

Project Zomboid
Shared: Survival · Sandbox · Building