Games like Final Shelter
Games like Final Shelter include Undertale, LISA: The Painful, Plague Inc: Evolved, Terraria, and OMORI. We matched them by the tags players give Final Shelter on Steam (RPG, Party-Based RPG, Outbreak Sim, 2D, and Memes): closest matches first, and among equally close ones the better-known games.

Undertale
Shared: RPG · 2D · Multiple Endings

LISA: The Painful
Shared: RPG · Post-apocalyptic · Party-Based RPG

Plague Inc: Evolved
Shared: Outbreak Sim · Post-apocalyptic · Indie

Terraria
Shared: 2D · Multiplayer · PvP

OMORI
Shared: RPG · 2D · Multiple Endings

Fallout 76
Shared: RPG · Post-apocalyptic · Multiplayer

Project Zomboid
Shared: Post-apocalyptic · RPG · Multiplayer

Don't Starve Together
Shared: RPG · 2D · Multiplayer

Legend of Mortal
Shared: RPG · Multiple Endings · Choices Matter

Pit People®
Shared: 2D · Memes · RPG

For The King
Shared: RPG · Party-Based RPG · Multiplayer

Baldur's Gate 3
Shared: RPG · Choices Matter · Multiplayer

The Henry Stickmin Collection
Shared: Memes · Multiple Endings · 2D

Dragon Age: Origins - Ultimate Edition
Shared: RPG · Party-Based RPG · Choices Matter

For The King II
Shared: RPG · Party-Based RPG · Multiplayer

Town of Salem
Shared: RPG · 2D · Multiplayer

Wartales
Shared: RPG · Party-Based RPG · Co-op

Pathfinder: Kingmaker - Enhanced Plus Edition
Shared: RPG · Party-Based RPG · Choices Matter

Baldur's Gate II: Enhanced Edition
Shared: RPG · Party-Based RPG · Choices Matter

Tom Clancy’s The Division™
Shared: RPG · Post-apocalyptic · Multiplayer

Aliya: Timelink
Shared: RPG · 2D · Multiple Endings

Castle Crashers®
Shared: 2D · Co-op · PvP

Wasteland 3
Shared: RPG · Post-apocalyptic · Party-Based RPG

Stardew Valley
Shared: RPG · Multiplayer · 2D