There’s an old (not sure how old) sci-fi novel by the likes of Larry Niven or Poul Anderson that Half-Life 2 really reminds me of. I was trying to tell someone about it, but I can’t remember the title or author and it’s driving me nuts. It chronicles the occupation of Earth by aliens, very like the Combine, over about 100 years. It focused mainly on several generations of a family who live on a sort of country estate in California, and are involved in various resistance movements over the years. The aliens set up a puppet government, restrict breeding, and kick everyone out of the cities so they can live in them and do whatever it is they’re on Earth to do.
There’s a chapter where a powerful human in the puppet government, a real nerdy (and evil!) guy is assassinated by a girl he had a crush on before the invasion. There’s another chapter late in the book about an Arab who has been basically raised from birth to be an assassin, to try and take a shot at one of the alien leaders.
Does this ring a bell with anyone?