Games like Gunboat God
Games like Gunboat God include Planes, Bullets and Vodka, Vampire Survivors, LUFTRAUSERS, Cyberhunt, and Geometry Wars: Retro Evolved. We matched them by the tags players give Gunboat God on Steam (Shoot 'Em Up, Bullet Hell, Stylized, Indie, and Cartoony): closest matches first, and among equally close ones the better-known games.

Planes, Bullets and Vodka
Shared: Shoot 'Em Up · Bullet Hell · Retro

Vampire Survivors
Shared: Bullet Hell · Indie · 2D

LUFTRAUSERS
Shared: Bullet Hell · Indie · Shoot 'Em Up

Cyberhunt
Shared: Indie · Shoot 'Em Up · Twin Stick Shooter

Geometry Wars: Retro Evolved
Shared: Bullet Hell · Twin Stick Shooter · Shoot 'Em Up

Bit Blaster XL
Shared: Shoot 'Em Up · Bullet Hell · Arcade

ZeroRanger
Shared: Shoot 'Em Up · Bullet Hell · Indie

Nova Drift
Shared: Shoot 'Em Up · Bullet Hell · Arcade

Cuphead
Shared: Indie · Bullet Hell · 2D

Beat Hazard
Shared: Bullet Hell · Shoot 'Em Up · Twin Stick Shooter

Exit the Gungeon
Shared: Indie · Bullet Hell · Arcade

Revolution Ace
Shared: Shoot 'Em Up · Bullet Hell · Indie

DRAINUS
Shared: Shoot 'Em Up · Indie · Bullet Hell

Broforce
Shared: Indie · 2D · Action

Enter the Gungeon
Shared: Bullet Hell · Indie · Twin Stick Shooter

METAL SLUG
Shared: Shoot 'Em Up · Arcade · 2D

Star Saviors
Shared: Shoot 'Em Up · Bullet Hell · Indie

Shovel Knight: Treasure Trove
Shared: Indie · Retro · 2D

Waves
Shared: Shoot 'Em Up · Bullet Hell · Twin Stick Shooter

Blazing Chrome
Shared: Shoot 'Em Up · Retro · Indie

Ikaruga
Shared: Shoot 'Em Up · Bullet Hell · Arcade

Huntdown
Shared: Shoot 'Em Up · Shooter · Retro

BALL x PIT
Shared: Bullet Hell · Shoot 'Em Up · Arcade

Pizza Tower
Shared: Indie · Cartoony · 2D