Games like Cellyon: Boss Confrontation
Games like Cellyon: Boss Confrontation include ELDEN RING, Monster Hunter: World, MONSTER HUNTER RISE, Orcs Must Die! 2, and Mount & Blade II: Bannerlord. We matched them by the tags players give Cellyon: Boss Confrontation on Steam (Online Co-Op, RPG, Difficult, Action, and Indie): closest matches first, and among equally close ones the better-known games.

ELDEN RING
Shared: RPG · Difficult · Online Co-Op

Monster Hunter: World
Shared: RPG · Action · Multiplayer

MONSTER HUNTER RISE
Shared: Online Co-Op · Action · RPG

Orcs Must Die! 2
Shared: Online Co-Op · Action · RPG

Mount & Blade II: Bannerlord
Shared: RPG · Strategy · Action

Bloons TD 6
Shared: Online Co-Op · Strategy · Multiplayer

Don't Starve Together
Shared: Online Co-Op · Difficult · Multiplayer

Ravenswatch
Shared: Online Co-Op · Action · Difficult

Monster Hunter Wilds
Shared: Online Co-Op · Action · Multiplayer

Remnant: From the Ashes
Shared: RPG · Action · Online Co-Op

ELDEN RING NIGHTREIGN
Shared: Online Co-Op · Action · Multiplayer

Torchlight II
Shared: RPG · Online Co-Op · Action

Magicka
Shared: Online Co-Op · Action · RPG

Borderlands 3
Shared: RPG · Online Co-Op · Action

PAYDAY 2
Shared: Action · Online Co-Op · Multiplayer

Mount & Blade: Warband
Shared: RPG · Action · Strategy

HELLDIVERS™ 2
Shared: Online Co-Op · Action · Multiplayer

PUBG: BATTLEGROUNDS
Shared: Online Co-Op · Action · Multiplayer

Gunfire Reborn
Shared: Online Co-Op · Indie · Action

DARK SOULS™ II: Scholar of the First Sin
Shared: RPG · Difficult · Action

For The King
Shared: Online Co-Op · RPG · Strategy

Valheim
Shared: Online Co-Op · Multiplayer · Difficult

A Dance of Fire and Ice
Shared: Level Editor · Difficult · Indie

Dungeon Defenders
Shared: Online Co-Op · Strategy · Multiplayer