In order for you to play Sky Force Anniversary on Linux with minimal graphics settings, your computer must meet the following requirements
Operating System:
Ubuntu 12.04+ 32/64 - bit / SteamOS+
Processor (CPU):
Core 2 Duo - 2.4 GHz or AMD equivalent
Memory (RAM):
2 GB RAM
Graphics Card:
OpenGL 2.1+ compatible graphics card
Storage:
400 MB available space