In order for you to play Graveyard Keeper on Linux with minimal graphics settings, your computer must meet the following requirements
Operating System:
Ubuntu 18.04, CentOS 7
Processor (CPU):
Intel core i5, 1.5 GHz and up
Memory (RAM):
4 GB RAM
Graphics Card:
1 Gb dedicated video card, shader model 3.0+
Storage:
1 GB available space