Games like Vermitron
Games like Vermitron include BALL x PIT, Relic Hunters Zero: Remix, Halo: Spartan Assault, Escape From Duckov, and Chippy. We matched them by the tags players give Vermitron on Steam (Twin Stick Shooter, Tower Defense, Top-Down Shooter, Action, and Arcade): closest matches first, and among equally close ones the better-known games.

BALL x PIT
Shared: Action · Arcade · Bullet Hell

Relic Hunters Zero: Remix
Shared: Twin Stick Shooter · Top-Down Shooter · Action

Halo: Spartan Assault
Shared: Top-Down Shooter · Action · Twin Stick Shooter

Escape From Duckov
Shared: Action · Top-Down Shooter · Adventure

Chippy
Shared: Twin Stick Shooter · Top-Down Shooter · Bullet Hell

Cyberhunt
Shared: Action · Twin Stick Shooter · Arcade

The Ascent
Shared: Top-Down Shooter · Action · Twin Stick Shooter

X-Morph: Defense
Shared: Tower Defense · Action · Twin Stick Shooter

Enter the Gungeon
Shared: Bullet Hell · Twin Stick Shooter · Pixel Graphics

Exit the Gungeon
Shared: Arcade · Action · Bullet Hell

State of Anarchy: Master of Mayhem
Shared: Top-Down Shooter · Twin Stick Shooter · Action

Kill The Crows
Shared: Action · Top-Down Shooter · Arcade

Nex Machina
Shared: Twin Stick Shooter · Action · Arcade

UBERMOSH
Shared: Action · Arcade · Twin Stick Shooter

SYNTHETIK: Legion Rising
Shared: Top-Down Shooter · Action · Twin Stick Shooter

UBERMOSH Vol.5
Shared: Action · Arcade · Top-Down Shooter

Deployment
Shared: Top-Down Shooter · Twin Stick Shooter · Action

Yet Another Zombie Defense HD
Shared: Tower Defense · Top-Down Shooter · Twin Stick Shooter

UBERMOSH Vol.3
Shared: Action · Arcade · Twin Stick Shooter

WOWOWOW KORONE BOX
Shared: Twin Stick Shooter · Action · Top-Down Shooter

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

Vampire Survivors
Shared: Bullet Hell · Pixel Graphics · Arcade

Sektori
Shared: Twin Stick Shooter · Arcade · Top-Down Shooter

Taur
Shared: Tower Defense · Action · Base Building