In order for you to play Sheltered on Linux with minimal graphics settings, your computer must meet the following requirements
Operating System:
Ubuntu 12.04 64-bit / Ubuntu 14.04 32-bit or later
Processor (CPU):
Dual Core CPU or higher
Memory (RAM):
2 GB RAM
Graphics Card:
GeForce 7800, AMD HD 4600, Intel HD Graphics 3000 or above
Storage:
650 MB available space