In order for you to play Zombie Panic! Source on Linux with minimal graphics settings, your computer must meet the following requirements
Operating System:
Latest Ubuntu LTS or higher or equivalent
Processor (CPU):
2.4 GHz Dual Core or better
Memory (RAM):
2 GB RAM
Graphics Card:
OpenGL compatible with Shader Model 2.0 support
Network:
Broadband Internet connection
Storage:
8 GB available space