Games like Circulo
Games like Circulo include Vampire Survivors, BALL x PIT, Deep Rock Galactic: Survivor, Brotato, and Enter the Gungeon. We matched them by the tags players give Circulo on Steam (Action, Action Roguelike, Bullet Hell, Top-Down Shooter, and 2D): closest matches first, and among equally close ones the better-known games.

Vampire Survivors
Shared: Action Roguelike · Bullet Hell · 2D

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

Deep Rock Galactic: Survivor
Shared: Action Roguelike · Bullet Hell · Top-Down Shooter

Brotato
Shared: Bullet Hell · Action Roguelike · Singleplayer

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

Megabonk
Shared: Action Roguelike · Bullet Hell · Action

Nuclear Throne
Shared: Action Roguelike · Action · Bullet Hell

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

Skul: The Hero Slayer
Shared: Action · Action Roguelike · 2D

The Binding of Isaac
Shared: Action Roguelike · Action · Roguelike

Nova Drift
Shared: Bullet Hell · Action Roguelike · Arcade

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

Glyphica: Typing Survival
Shared: Action Roguelike · Bullet Hell · Action

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

Rocket Rats
Shared: Action Roguelike · Bullet Hell · Action

Rogue Legacy
Shared: Action Roguelike · Action · Roguelike

Yet Another Zombie Survivors
Shared: Action Roguelike · Top-Down Shooter · Arcade

Hades
Shared: Action Roguelike · Action · Singleplayer

Maniac
Shared: Action Roguelike · Top-Down Shooter · Singleplayer

Windowkill
Shared: Action · Action Roguelike · Bullet Hell

Slime 3K: Rise Against Despot
Shared: Action Roguelike · Bullet Hell · 2D

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

Tiny Rogues
Shared: Action Roguelike · Bullet Hell · Top-Down Shooter

Boneraiser Minions
Shared: Action Roguelike · Bullet Hell · 2D