Games like FRONTIERS
Games like FRONTIERS include Fallout 4, Terraria, Rust, Slime Rancher, and The Long Dark. We matched them by the tags players give FRONTIERS on Steam (RPG, Adventure, Indie, Casual, and Open World): closest matches first, and among equally close ones the better-known games.

Fallout 4
Shared: RPG · Open World · Adventure

Terraria
Shared: Adventure · Sandbox · Survival

Rust
Shared: Open World · Survival · Adventure

Slime Rancher
Shared: Adventure · Exploration · Open World

The Long Dark
Shared: Open World · Survival · Exploration

No Man's Sky
Shared: Open World · Exploration · Adventure

The Forest
Shared: Adventure · Open World · Survival

The Scroll of Taiwu : Beyond The Dome
Shared: RPG · Open World · Indie

Don't Starve Together
Shared: Adventure · Survival · Open World

Starbound
Shared: Adventure · Sandbox · Survival

Keplerth
Shared: Adventure · Exploration · Sandbox

Tainted Grail: The Fall of Avalon
Shared: RPG · Adventure · Open World

Fallout: New Vegas
Shared: RPG · Open World · Exploration

Palworld
Shared: Open World · Survival · Indie

Don't Starve
Shared: Adventure · Indie · Survival

My Time at Portia
Shared: RPG · Open World · Casual

Enshrouded
Shared: Open World · RPG · Adventure

7 Days to Die
Shared: Open World · Survival · RPG

Sons Of The Forest
Shared: Open World · Survival · Adventure

Valheim
Shared: Open World · Survival · Adventure

Core Keeper
Shared: Open World · Exploration · Survival

The Elder Scrolls IV: Oblivion Remastered
Shared: RPG · Adventure · Open World

The Elder Scrolls IV: Oblivion® Game of the Year Edition (2009)
Shared: RPG · Open World · Adventure

Last Oasis
Shared: RPG · Open World · Adventure