Games like Octogun - Idle
Games like Octogun - Idle include Vampire Survivors, Brotato, Shelldiver, BALL x PIT, and DJMAX RESPECT V. We matched them by the tags players give Octogun - Idle on Steam (Action, Casual, Singleplayer, 2D, and Arena Shooter): closest matches first, and among equally close ones the better-known games.

Vampire Survivors
Shared: 2D · Bullet Hell · Singleplayer

Brotato
Shared: Singleplayer · Bullet Hell · Arena Shooter

Shelldiver
Shared: Casual · Idler · 2D

BALL x PIT
Shared: Action · Bullet Hell · Arcade

DJMAX RESPECT V
Shared: Casual · Action · Singleplayer

Megabonk
Shared: Action · Singleplayer · Bullet Hell

Timberman
Shared: Casual · Action · 2D

Keep on Mining!
Shared: Casual · Idler · Singleplayer

Zup! S
Shared: Casual · 2D · Singleplayer

Planes, Bullets and Vodka
Shared: Action · Casual · 2D

A Dance of Fire and Ice
Shared: Singleplayer · 2D · Casual

Cyberhunt
Shared: Action · Casual · 2D

Rocket Rats
Shared: Casual · Action · 2D

Melvor Idle
Shared: Casual · Idler · Singleplayer

20 Minutes Till Dawn
Shared: Bullet Hell · Top-Down Shooter · Singleplayer

Skul: The Hero Slayer
Shared: Action · 2D · Singleplayer

Muse Dash
Shared: Casual · Singleplayer · 2D

Boneraiser Minions
Shared: 2D · Bullet Hell · Singleplayer

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

Glyphica: Typing Survival
Shared: Action · Arena Shooter · Top-Down Shooter

LUFTRAUSERS
Shared: Action · 2D · Bullet Hell

One Finger Death Punch
Shared: Action · Singleplayer · 2D

Sixtar Gate: STARTRAIL
Shared: Action · Casual · 2D

Kingdom Rush - Tower Defense
Shared: Singleplayer · 2D · Casual