In order for you to play Enter the Gungeon on Linux with minimal graphics settings, your computer must meet the following requirements
Operating System:
Ubuntu 12.04 or later
Processor (CPU):
Intel Core 2 Duo E6320 (2*1866) or equivalent
Memory (RAM):
2 GB RAM
Graphics Card:
GeForce 7600 GS (512 MB) or equivalent
Storage:
2 GB available space