Official specs from Steam

Castle Crashers system requirements

Minimum and recommended PC specs as listed by the developer on Steam. Native macOS version available.

Castle Crashers release infoSteam page Check other games

Minimum

OSMicrosoft® Windows® 10
ProcessorIntel Core 2 Duo 2GHz+ or better
Memory8 GB RAM
Graphics2GB RAM
DirectX®9.0c
Hard Drive512 MB HD space
SoundDirectX compatible
Other RequirementsBroadband Internet connection
AdditionalSupports Direct Input compatible controllers
AdditionalUltra Graphics Mode requires a 64-bit OS, at least 8GB of RAM, and 2GB VRAM.

macOS minimum

OSmacOS 10.15 - Catalina
Processori5 2.3GHz+ or better
Memory8 GB RAM
Graphics2GB RAM
Hard Drive512 MB HD space
SoundMac compatible sound card
Other RequirementsBroadband Internet connection
AdditionalWith the right drivers the game supports Microsoft® Xbox 360, Sony PS3, and Logitech controllers
AdditionalUltra Graphics Mode requires a 64-bit OS, at least 8GB of RAM, and a 2GB VRAM.

FAQ

What graphics card do I need for Castle Crashers?

Minimum: 2GB RAM.

How much RAM does Castle Crashers need?

Castle Crashers needs 8 GB RAM at minimum.

How big is Castle Crashers?

Castle Crashers requires 512 MB HD space.

Does Castle Crashers run on Mac or Steam Deck/Linux?

Yes, there is a native macOS version. There is no native Linux build (Proton compatibility may vary).