Games like B99
Games like B99 include Hades, The Binding of Isaac, Hades II, Skul: The Hero Slayer, and Risk of Rain (2013). We matched them by the tags players give B99 on Steam (Action, Roguelike, Action Roguelike, Psychedelic, and Indie): closest matches first, and among equally close ones the better-known games.

Hades
Shared: Action Roguelike · Action · Indie

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

Hades II
Shared: Action · Roguelike · Action Roguelike

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

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

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

Rogue Legacy
Shared: Roguelike · Action · Action Roguelike

Vampire Survivors
Shared: Action Roguelike · Roguelike · Indie

Megabonk
Shared: Roguelike · Action Roguelike · Action

Ravenswatch
Shared: Roguelike · Action · Action Roguelike

Spelunky
Shared: Roguelike · Action Roguelike · Indie

Dungreed
Shared: Action Roguelike · Roguelike · Action

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

Nuclear Throne
Shared: Roguelike · Action Roguelike · Action

Streets of Rogue
Shared: Action Roguelike · Action · Roguelike

Gunfire Reborn
Shared: Roguelike · Action · Indie

Legend of Dungeon
Shared: Roguelike · Action Roguelike · Indie

Noita
Shared: Roguelike · Indie · Action

Brotato
Shared: Roguelike · Action Roguelike · Singleplayer

Killing Room
Shared: Action · Roguelike · Indie

Halls of Torment
Shared: Action Roguelike · Roguelike · Action

Sephiria
Shared: Action Roguelike · Roguelike · Action

Enter the Gungeon
Shared: Roguelike · Action Roguelike · Indie

Ancient Dungeon
Shared: VR · Action · Roguelike