Games like Odyssey Moon
Games like Odyssey Moon include Vampire Survivors, BALL x PIT, Megabonk, Enter the Gungeon, and Halls of Torment. We matched them by the tags players give Odyssey Moon on Steam (Action Roguelike, Action, Bullet Hell, Arcade, and Roguelike): closest matches first, and among equally close ones the better-known games.

Vampire Survivors
Shared: Action Roguelike · Bullet Hell · 2D

BALL x PIT
Shared: Action · Bullet Hell · Arcade

Megabonk
Shared: Action Roguelike · Roguelike · Bullet Hell

Enter the Gungeon
Shared: Action Roguelike · Bullet Hell · Roguelike

Halls of Torment
Shared: Action Roguelike · Bullet Hell · Action

Skul: The Hero Slayer
Shared: Action · Action Roguelike · Roguelike

Rogue Legacy
Shared: Action Roguelike · Action · Roguelike

Death Must Die
Shared: Action Roguelike · Bullet Hell · Action

The Binding of Isaac: Rebirth
Shared: Action Roguelike · Roguelike · Indie

Nuclear Throne
Shared: Action Roguelike · Roguelike · Bullet Hell

Boneraiser Minions
Shared: Action Roguelike · Bullet Hell · 2D

Nova Drift
Shared: Bullet Hell · Action Roguelike · Arcade

Brotato
Shared: Action Roguelike · Bullet Hell · Roguelike

Risk of Rain Returns
Shared: Action Roguelike · 2D · Action

Dungreed
Shared: Action Roguelike · Action · Roguelike

Soulstone Survivors
Shared: Action Roguelike · Bullet Hell · Roguelike

Atomicrops
Shared: Action · Bullet Hell · Roguelike

Dead Cells
Shared: Action Roguelike · Roguelike · 2D

Risk of Rain (2013)
Shared: Action Roguelike · Action · Roguelike

Rabbit and Steel
Shared: Action Roguelike · Bullet Hell · Roguelike

Rocket Rats
Shared: Action Roguelike · Bullet Hell · Action

Windowkill
Shared: Action · Action Roguelike · Bullet Hell

Hades
Shared: Action Roguelike · Action · Roguelike