Once Human Wiki - System Requirements
Minimum
OSWindows 10 64-bit
ProcessorIntel Core i5-4460
Memory8 GB
GraphicsNVIDIA GeForce GTX 750 Ti / AMD Radeon RX 550
Storage70 GB
Recommended
OSWindows 10 64-bit
ProcessorIntel Core i7-7700
Memory16 GB
GraphicsNVIDIA GeForce GTX 1060 (6GB) / AMD Radeon RX 580
Storage70 GB
Source: Official Steam store page, confirmed unanimous across 6+ independent sources