After reading the novella, Army of One, I decided to pick up the first book in the series. It’s a wild ride. But I’ll save you the agony of having to decide if you want to start a 12-book series (12!!) — don’t bother I didn’t even finish the fourth book.
Publisher’s Summary
Earth arms marines with alien technology and builds its first battle fleet! Kyle Riggs is snatched by an alien spacecraft sometime after midnight. The ship is testing everyone it catches and murdering the weak. The good news is that Kyle keeps passing tests and staying alive. The bad news is the aliens who sent this ship are the nicest ones out there.
A novel of military science fiction by best-selling author B. V. Larson, Swarm is the story of Earth’s annexation by an alien empire. Long considered a primitive people on a backwater planet, humanity finds itself in the middle of a war – and faced with extinction.