In order for you to play Bad Rats: the Rats' Revenge on Windows with minimal graphics settings, your computer must meet the following requirements
OS *:
Windows XP or Vista
Processor (CPU):
Pentium IV 1.6 GHz or better (dual core recommended)
Memory (RAM):
512MB RAM (1GB recommended)
Graphics Card:
DirectX®9-compatible graphics adapter with 128 MB (256 MB recommended)
DirectX®:
9 or better
Hard Drive:
300MB
Sound:
DirectX®9-compatible