Games like Big Mushroom RPG
Games like Big Mushroom RPG include Baldur's Gate 3, Warhammer 40,000: Rogue Trader, Solasta: Crown of the Magister, STAR WARS™ Knights of the Old Republic™ II - The Sith Lords™, and The Elder Scrolls IV: Oblivion® Game of the Year Edition (2009). We matched them by the tags players give Big Mushroom RPG on Steam (RPG, Moddable, Adventure, Character Customization, and Choices Matter): closest matches first, and among equally close ones the better-known games.

Baldur's Gate 3
Shared: RPG · Character Customization · Choices Matter

Warhammer 40,000: Rogue Trader
Shared: RPG · Choices Matter · Character Customization

Solasta: Crown of the Magister
Shared: RPG · Character Customization · Adventure

STAR WARS™ Knights of the Old Republic™ II - The Sith Lords™
Shared: RPG · Choices Matter · Adventure

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

Fallout: New Vegas
Shared: RPG · Moddable · Adventure

Dragon Age: Origins - Ultimate Edition
Shared: RPG · Choices Matter · Character Customization

The Witcher 3: Wild Hunt — Remastered
Shared: RPG · Adventure · Choices Matter

Hogwarts Legacy
Shared: RPG · Adventure · Character Customization

Dragon Age™ Inquisition
Shared: RPG · Character Customization · Choices Matter

Tainted Grail: The Fall of Avalon
Shared: RPG · Adventure · Character Customization

Shadow Gambit: The Cursed Crew
Shared: RPG · Character Customization · Choices Matter

GreedFall
Shared: RPG · Character Customization · Choices Matter

Quasimorph
Shared: RPG · Choices Matter · Turn-Based Strategy

The Elder Scrolls IV: Oblivion Remastered
Shared: RPG · Adventure · Character Customization

South Park™: The Stick of Truth™
Shared: RPG · Adventure · 2D

Pathfinder: Kingmaker - Enhanced Plus Edition
Shared: RPG · Character Customization · Choices Matter

Mount & Blade II: Bannerlord
Shared: RPG · Character Customization · Moddable

Starfield
Shared: RPG · Character Customization · Singleplayer

Metaphor: ReFantazio
Shared: RPG · Adventure · Turn-Based Combat

Dragon Age II: Ultimate Edition
Shared: RPG · Adventure · Character Customization

Wartales
Shared: RPG · Turn-Based Strategy · Adventure

Mass Effect™ Legendary Edition
Shared: RPG · Choices Matter · Character Customization

Avowed
Shared: RPG · Adventure · Character Customization