Windows

MINIMUM:
Requires a 64-bit processor and operating system
OS: Windows 7
Processor: Core 2 Duo
Memory: 3 GB RAM
Graphics: SM4, 512MB VRAM
DirectX: Version 11
Storage: 1 GB available space

RECOMMENDED:
Requires a 64-bit processor and operating system
OS: Windows 10
Processor: Core i5
Memory: 4 GB RAM
Graphics: SM4, 1GB VRAM
DirectX: Version 11
Storage: 1 GB available space

Mac OS X

MINIMUM:
Requires a 64-bit processor and operating system
OS: Mavericks (10.9)
Processor: Intel
Memory: 3 GB RAM
Graphics: Metal, 512MB VRAM
Storage: 1 GB available space

RECOMMENDED:
Requires a 64-bit processor and operating system
OS: Yosemite (10.10)
Processor: Intel Core i5
Memory: 4 GB RAM
Graphics: Metal, 1GB VRAM
Storage: 1 GB available space

There has been questioning around if the game will be on 32bit. The anwser is No.

Mikeska [developer] 19 Oct @ 10:45pm
Originally posted by neil501:
are you going to make it in 32bit version too like your other games?
64-bit only is the current plan