Biotic Defenders

You play a nanobot inside a human body, sent in to kill viruses as part of a medical experiment and scored on how efficiently you manage it. The framing matters more than it usually would: this is a score-attack shooter, so the goal is not merely to clear a level but to clear it cleanly, and the boss waiting at the end measures how well you have been playing all along. Biotic Defenders is compact, quick, and built to be replayed rather than finished.