In order for you to play X3: Reunion on Linux with minimal graphics settings, your computer must meet the following requirements
Operating System:
Ubuntu 12.04 LTS
Processor (CPU):
Pentium® IV or AMD® equivalent at 2.0 GHz
Memory (RAM):
1 GB RAM
Graphics Card:
256MB OpenGL 2.0+ discrete NVIDIA/AMD card (with proprietary driver) or Intel Core i7-2620M with Mesa 9.0
Hard Drive:
10 GB of free space
In order to play X3: Reunion on Linux with maximum graphics settings, you need a computer with a configuration no worse than the following
Operating System:
Ubuntu 12.04 LTS
Processor (CPU):
Intel® Core™ 2 Duo or AMD® equivalent at 2.0 GHz
Memory (RAM):
3 GB RAM
Graphics Card:
512MB OpenGL 3.0+ discrete NVIDIA/AMD card (with proprietary driver)
Hard Drive:
10 GB of free space