Games like Extermination
Games like Extermination include Deep Rock Galactic: Survivor, Monsters are Coming!, Glyphica: Typing Survival, Vampire Survivors, and BALL x PIT. We matched them by the tags players give Extermination on Steam (Arena Shooter, Bullet Hell, Roguelite, Tower Defense, and PvE): closest matches first, and among equally close ones the better-known games.

Deep Rock Galactic: Survivor
Shared: Roguelite · Bullet Hell · Arena Shooter

Monsters are Coming!
Shared: Roguelite · Tower Defense · Bullet Hell

Glyphica: Typing Survival
Shared: Arena Shooter · Bullet Hell · Roguelite

Vampire Survivors
Shared: Bullet Hell · Roguelite · Action

BALL x PIT
Shared: Roguelite · Bullet Hell · Action

Megabonk
Shared: Roguelite · Bullet Hell · Action

Shape of Dreams
Shared: Roguelite · PvE · Action

Vital Shell
Shared: Roguelite · Bullet Hell · Arena Shooter

Soulstone Survivors
Shared: Roguelite · Bullet Hell · Action

Nova Drift
Shared: Bullet Hell · Roguelite · Arena Shooter

Rogue: Genesia
Shared: Bullet Hell · Roguelite · PvE

Brotato
Shared: Bullet Hell · Arena Shooter · Roguelite

Halls of Torment
Shared: Bullet Hell · Roguelite · Action

Arms of God
Shared: Bullet Hell · Arena Shooter · Roguelite

FatalZone
Shared: Bullet Hell · Roguelite · Arena Shooter

The Spell Brigade
Shared: Roguelite · Bullet Hell · Action

Magicraft
Shared: Bullet Hell · Roguelite · Top-Down

Death Must Die
Shared: Bullet Hell · Roguelite · Action

God Of Weapons
Shared: Roguelite · Bullet Hell · Arena Shooter

Necrosmith
Shared: Roguelite · Tower Defense · Bullet Hell

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

Bloodshed
Shared: Bullet Hell · Arena Shooter · Action

Noobs Are Coming
Shared: Arena Shooter · Roguelite · Bullet Hell

Tiny Rogues
Shared: Bullet Hell · Roguelite · Top-Down