Games like Shyondemic
Games like Shyondemic include Undertale, OMORI, Rogue Legacy, The Vagrant, and Hades II. We matched them by the tags players give Shyondemic on Steam (Side Scroller, PvE, Roguelike, Female Protagonist, and RPG): closest matches first, and among equally close ones the better-known games.

Undertale
Shared: RPG · Choices Matter · Story Rich

OMORI
Shared: RPG · Story Rich · Horror

Rogue Legacy
Shared: Roguelike · 2D · RPG

The Vagrant
Shared: Female Protagonist · Side Scroller · RPG

Hades II
Shared: Roguelike · Female Protagonist · RPG

Tales of the Black Forest
Shared: RPG · Horror · Female Protagonist

Volcano Princess
Shared: Female Protagonist · RPG · Choices Matter

ICEY
Shared: Female Protagonist · Side Scroller · 2D

Skul: The Hero Slayer
Shared: Roguelike · 2D · Side Scroller

Ib
Shared: Horror · 2D · RPG

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

Ten Trials of Babel: The Doppelganger Maze
Shared: Female Protagonist · RPG · Multiple Endings

Dex
Shared: Female Protagonist · RPG · Side Scroller

Legend of Mortal
Shared: RPG · Choices Matter · Lore-Rich

Oxenfree
Shared: Female Protagonist · Choices Matter · Story Rich

Angels of Death
Shared: Horror · RPG · 2D

The Witch's House MV
Shared: Horror · 2D · RPG

Bloodstained: Ritual of the Night
Shared: Female Protagonist · RPG · Side Scroller

Home Behind 2
Shared: Roguelike · RPG · Female Protagonist

Vampire Survivors
Shared: 2D · Roguelike · Pixel Graphics

Noita
Shared: Roguelike · 2D · Pixel Graphics

Child of Light
Shared: RPG · Female Protagonist · 2D

Crypt of the NecroDancer
Shared: Roguelike · Female Protagonist · RPG