Games like Monstergasm
Games like Monstergasm include Planes, Bullets and Vodka, BALL x PIT, SNKRX, Nova Drift, and Chippy. We matched them by the tags players give Monstergasm on Steam (Action, Casual, Arena Shooter, Shoot 'Em Up, and Dark Fantasy): closest matches first, and among equally close ones the better-known games.

Planes, Bullets and Vodka
Shared: Action · Casual · Shoot 'Em Up

BALL x PIT
Shared: Action · Shoot 'Em Up · Top-Down Shooter

SNKRX
Shared: Arena Shooter · Shoot 'Em Up · Top-Down Shooter

Nova Drift
Shared: Shoot 'Em Up · Arena Shooter · Bullet Hell

Chippy
Shared: Arena Shooter · Shoot 'Em Up · Top-Down Shooter

Cyberhunt
Shared: Action · Casual · Shoot 'Em Up

Bit Blaster XL
Shared: Shoot 'Em Up · Action · Casual

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

State of Anarchy: Master of Mayhem
Shared: Action · Top-Down Shooter · Shoot 'Em Up

Sky Force Reloaded
Shared: Shoot 'Em Up · Action · Top-Down Shooter

Arms of God
Shared: Arena Shooter · Action · Top-Down Shooter

State of Anarchy
Shared: Action · Casual · Shoot 'Em Up

Time Wasters
Shared: Arena Shooter · Shoot 'Em Up · Casual

Deep Rock Galactic: Survivor
Shared: Top-Down Shooter · Arena Shooter · Action

Pikuniku
Shared: Casual · Action · Puzzle

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

20 Minutes Till Dawn
Shared: Shoot 'Em Up · Top-Down Shooter · Bullet Hell

Insect Swarm
Shared: Shoot 'Em Up · Top-Down · Top-Down Shooter

驱煞
Shared: Casual · Action · Top-Down Shooter

Titan Attacks!
Shared: Arena Shooter · Shoot 'Em Up · Top-Down Shooter

Minishoot' Adventures
Shared: Top-Down · Casual · Bullet Hell

Vampire Survivors
Shared: Casual · Bullet Hell · Action

Bot Vice
Shared: Shoot 'Em Up · Top-Down Shooter · Action-Adventure

WOWOWOW KORONE BOX
Shared: Action · Shoot 'Em Up · Top-Down Shooter