When You Get Old, Go Out into the Universe and Kill Stuff

If you're looking of something fun, fast, and thoroughly entertaining, I highly recommend John Scalzi's sci-fi novel Old Man's War . . . it definitely has a Starship Troopers feel, but it's even funnier (and also-- at times-- quite touching, especially about the subject of marriage) but mainly it's about old folks abandoning earth for the Colonial Defense Forces, where they will be somehow outfitted to fight hostile aliens throughout a "dark forest" type universe-- I won't spoil just how these geriatrics are transformed into soldiers, but once it happens, then the fun begins-- so much fun that there is quite a bit of criticism and debate about the book . . . some liberal reviewers claim the book lauds jingoistic fervor and overly-aggressive, xenophobic tactics towards the other, and these ideas certainly weigh on the protagonist-- especially when he's stomping the one inch tall (but highly aggressive) Covandu to death . . . supposedly, the rest of the series sorts out these controversial themes, but this book is also great as a stand-alone.