In order for you to play Zombie Panic! Source on Windows with minimal graphics settings, your computer must meet the following requirements
Operating System:
Windows 10/11
Processor (CPU):
2.4 GHz Dual Core or better
Memory (RAM):
2 GB RAM
Graphics Card:
Shader Model 3.0 support (NVIDIA 7600, ATI X1600 or better)
DirectX:
Version 9.0c
Network:
Broadband Internet connection
Storage:
8 GB available space