I'm a sucker for science fiction, but after a while movies and games get predictable. Aliens try to take over the world but in the end humans always win. Destroy All Humans! was different; it allowed you to play as Cryptosporidium-137 (who was named after a particularly nasty infection - do feel free to check Wikipedia for all the gory details), a member of the Grey-like Furon race who are hell-bent on the invasion of Earth. They also needed the brainstems of humans which contain precious strands of Furon DNA to ensure the continuation of their race.
As Crypto caused devastation though fifties America, where the inhabitants lived in terror of the Red Menace (that's the communists of Russia to you and me), you got to mutilate cows, abduct anyone who took your fancy, use psychic abilities to coerce or just murder innocent human fodder, and play with various toys including an anal probe, a flying saucer and a Disintegrator Ray which vaporised anyone and anything in its path.
Destroy All Humans! 2 picks up ten years later during the swinging sixties. Cryptosporidium-138 has been masquerading as the President and enjoying his new genitalia made from the finest Furon DNA while his brainy companion, Orthopox, watches from their saucer. All should be well during the Summer of Love but the Russians have other ideas. They shoot down the Furon saucer, leaving Crypto marooned and Pox dead (although still able to boss Crypto about from as a holographic projection).