Biology Battle (Steam key/Region free).

http://store.steampowered.com/app/335080/
In this classic space-shooter, you take the role of a medical nanobot and embark on an exciting journey into the depths of a biological cell. Evade the defense tactics of the other cells and try to survive for as long as possible.

Features:
Eleven different versus modes (e.g. lasso, froghop, worms)
Play online against thousands of real opponents
Comprehensive tournament mode and demanding coop mode
Improve the ship´s capabilities with various bonuses
Adaption of the XBLA-hit