Games like Nex Machina
Games like Nex Machina include UBERMOSH, RUINER, Ikaruga, Enter the Gungeon, and Sky Force Reloaded. We matched them by the tags players give Nex Machina on Steam (Twin Stick Shooter, Bullet Hell, Action, Arcade, and Indie): closest matches first, and among equally close ones the better-known games.

UBERMOSH
Shared: Action · Great Soundtrack · Cyberpunk

RUINER
Shared: Action · Great Soundtrack · Twin Stick Shooter

Ikaruga
Shared: Bullet Hell · Arcade · Action

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

Sky Force Reloaded
Shared: Bullet Hell · Arcade · Shoot 'Em Up

Geometry Wars™ 3: Dimensions Evolved
Shared: Twin Stick Shooter · Action · Arcade

Cuphead
Shared: Great Soundtrack · Difficult · Bullet Hell

Waves
Shared: Bullet Hell · Twin Stick Shooter · Arcade

ZeroRanger
Shared: Bullet Hell · Action · Indie

Assault Android Cactus+
Shared: Twin Stick Shooter · Bullet Hell · Shoot 'Em Up

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

Nuclear Throne
Shared: Bullet Hell · Indie · Action

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

LUFTRAUSERS
Shared: Bullet Hell · Action · Arcade

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

BALL x PIT
Shared: Action · Bullet Hell · Arcade

Hotline Miami
Shared: Action · Great Soundtrack · Indie

Chippy
Shared: Twin Stick Shooter · Bullet Hell · Arcade

Touhou Tenkuushou ~ Hidden Star in Four Seasons.
Shared: Bullet Hell · Great Soundtrack · Shoot 'Em Up

SYNTHETIK: Legion Rising
Shared: Action · Indie · Twin Stick Shooter

Hotline Miami 2: Wrong Number
Shared: Great Soundtrack · Action · Difficult

Just Shapes & Beats
Shared: Bullet Hell · Great Soundtrack · Action

Touhou Koumakyou: New Classic - the Embodiment of Scarlet Devil
Shared: Bullet Hell · Action · Shoot 'Em Up

Vampire Survivors
Shared: Bullet Hell · Indie · Arcade