Ares Upwards

At some point just after the last ice age, one of the Martians' astronomers brings terrifying news to the Executive Committee. Intelligence has evolved on Earth.
It seems inevitable that the Earthlets will one day notice the entirely dry planet Mars, and, land-bound creatures that they are, leave their mostly wet planet to take up residence in the Martians' back yard. For the Martians the natural solution seems to be to get their retaliation in first by invading Earth and ensuring that technology there never develops to a troublesome degree.
Now, after several setbacks and 13,000 years after their plan's genesis, the invasion fleet is finally ready.
Timothy Linden PhD (physics) is smart. He's also bone idle, and works just hard enough to pay the rent while spending the rest of his time playing a particular computer game that he isn't very good at.Timothy generally despises most other humans and dislikes leaving his home.
Pity that the Martians have chosen him to be their Liaison Officer...Timothy's experience of the invasion rapidly spirals from slight irritation when the Martians interrupt his game to abject terror as he bounces from one mishap to the next, waiting to find out whether the British Government or the Martians will kill him first...