Currently $23.99 USD on steam.
SYSTEM REQUIREMENTS
MINIMUM:
OS: Windows Vista 64-bit
Processor: Intel Core 2 Quad 2.3 Ghz or AMD Phenom X4 2.3 Ghz or above
Memory: 4 GB RAM
Graphics: GPU that supports Shader Model 3.0
DirectX: Version 10
Storage: 13 GB available space
RECOMMENDED:
OS: Windows 7 Professional 64-bit, Windows 8 64-bit, Windows 8.1 64-bit
Processor: Intel/AMD Quad Core 2.3 Ghz or above
Memory: 8 GB RAM
Graphics: NVIDIA GeForce GTS 250 or AMD Radeon HD 2900
DirectX: Version 11
Storage: 13 GB available space