Games like Sidequest Survivors
Games like Sidequest Survivors include Vampire Survivors, Megabonk, Halls of Torment, Death Must Die, and Brotato. We matched them by the tags players give Sidequest Survivors on Steam (Bullet Heaven, Action Roguelike, Indie, Bullet Hell, and Pixel Graphics): closest matches first, and among equally close ones the better-known games.

Vampire Survivors
Shared: Action Roguelike · Bullet Hell · Pixel Graphics

Megabonk
Shared: Bullet Heaven · Action Roguelike · Indie

Halls of Torment
Shared: Action Roguelike · Bullet Hell · Pixel Graphics

Death Must Die
Shared: Action Roguelike · Bullet Hell · Bullet Heaven

Brotato
Shared: Action Roguelike · Bullet Hell · Bullet Heaven

The Binding of Isaac: Rebirth
Shared: Action Roguelike · Indie · Pixel Graphics

Soulstone Survivors
Shared: Bullet Heaven · Action Roguelike · Bullet Hell

Boneraiser Minions
Shared: Action Roguelike · Bullet Hell · Pixel Graphics

Skul: The Hero Slayer
Shared: Indie · Action Roguelike · Action

Hades
Shared: Action Roguelike · Indie · Roguelite

BALL x PIT
Shared: Action · Bullet Hell · Action Roguelike

Enter the Gungeon
Shared: Action Roguelike · Bullet Hell · Pixel Graphics

Dungreed
Shared: Action Roguelike · Pixel Graphics · Indie

Deep Rock Galactic: Survivor
Shared: Action Roguelike · Bullet Heaven · Bullet Hell

Nuclear Throne
Shared: Action Roguelike · Indie · Pixel Graphics

Tower of Babel: Survivors of Chaos
Shared: Bullet Heaven · Action Roguelike · Bullet Hell

Rogue Legacy
Shared: Indie · Action Roguelike · Action

Realm of the Mad God Exalt
Shared: Pixel Graphics · Bullet Hell · Action Roguelike

Yet Another Zombie Survivors
Shared: Bullet Heaven · Action Roguelike · Indie

Dead Cells
Shared: Action Roguelike · Pixel Graphics · Roguelite

Rogue: Genesia
Shared: Bullet Heaven · Action Roguelike · Bullet Hell

20 Minutes Till Dawn
Shared: Action Roguelike · Bullet Hell · Roguelite

Nova Drift
Shared: Bullet Hell · Action Roguelike · Bullet Heaven

UnderMine
Shared: Action Roguelike · Pixel Graphics · Indie