Games like Mighty No. 9
Games like Mighty No. 9 include Cuphead, Broforce, Mega Man 11, Shovel Knight: Treasure Trove, and Bloodstained: Ritual of the Night. We matched them by the tags players give Mighty No. 9 on Steam (Platformer, Action, Anime, Side Scroller, and 2.5D): closest matches first, and among equally close ones the better-known games.
Cuphead
Shared: Platformer · Co-op · Difficult
Broforce
Shared: Action · Platformer · Side Scroller
Mega Man 11
Shared: Platformer · Action · Side Scroller
Shovel Knight: Treasure Trove
Shared: Platformer · Retro · Action
Bloodstained: Ritual of the Night
Shared: Action · Anime · Platformer
ICEY
Shared: Action · Anime · Side Scroller
Sonic Mania
Shared: Platformer · Retro · Action
Hollow Knight
Shared: Platformer · Singleplayer · Indie
Gravity Circuit
Shared: Platformer · Action · Indie
BattleBlock Theater®
Shared: Platformer · Co-op · Multiplayer
Bloodstained: Curse of the Moon
Shared: Action · Platformer · Retro
Skul: The Hero Slayer
Shared: Action · Platformer · Indie
Azure Striker Gunvolt
Shared: Action · Platformer · Anime
Super Meat Boy
Shared: Platformer · Indie · Singleplayer
Geometry Dash
Shared: Platformer · Singleplayer · Difficult
My Friend Pedro
Shared: Action · Indie · Platformer
Freedom Planet
Shared: Platformer · Action · Retro
Angry Video Game Nerd Adventures
Shared: Platformer · Action · Indie
The Messenger
Shared: Platformer · Retro · Action
SANABI
Shared: Action · Platformer · Singleplayer
Intrusion 2
Shared: Action · Platformer · Indie
Deadlight
Shared: Platformer · Action · Side Scroller
Clone Drone in the Danger Zone
Shared: Action · Robots · Multiplayer
Out There Somewhere
Shared: Platformer · Action · Indie