Games like Retronaut
Games like Retronaut include Vampire Survivors, Deep Rock Galactic: Survivor, BALL x PIT, Megabonk, and Brotato. We matched them by the tags players give Retronaut on Steam (Action Roguelike, Action, Space, Roguelite, and Bullet Hell): closest matches first, and among equally close ones the better-known games.

Vampire Survivors
Shared: Action Roguelike · Roguelite · Bullet Hell

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

BALL x PIT
Shared: Action · Roguelite · Action Roguelike

Megabonk
Shared: Action Roguelike · Roguelite · Bullet Hell

Brotato
Shared: Action Roguelike · Bullet Hell · Roguelite

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

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

EVERSPACE™
Shared: Action Roguelike · Space · Action

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

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

Hades
Shared: Action Roguelike · Roguelite · Action

Risk of Rain Returns
Shared: Action Roguelike · 2D · Action

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

Nova Drift
Shared: Action Roguelike · Roguelite · Bullet Hell

暖雪 Warm Snow
Shared: Action Roguelike · Roguelite · 2D

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

Magicraft
Shared: Action Roguelike · Roguelite · Bullet Hell

Returnal™
Shared: Action · Bullet Hell · Action Roguelike

Rocket Rats
Shared: Action Roguelike · Bullet Hell · Roguelite

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

FatalZone
Shared: Action Roguelike · Bullet Hell · Roguelite

UnderMine
Shared: Action Roguelike · Roguelite · Action

Soulstone Survivors
Shared: Action Roguelike · Roguelite · Bullet Hell

Nuclear Throne
Shared: Action Roguelike · Action · Bullet Hell