Civilization, the Brilliant Stars

[Interstellar war + alien invasion + omniscient perspective]

For thousands of years, human civilization searched endlessly for traces of alien civilizations, but never found any. Humanity seemed like a lonely child lighting a bonfire in the desolate universe, hoping someone would find it. Yet it appeared that humans were the only intelligent civilization in the entire cosmos.

At last, one day, humanity received a mysterious message from beyond the solar system. It meant that we were not alone: other intelligent life existed in the universe!

[Greetings, newly risen Type III civilization! ... But our empire still wishes to tell you one fact: the truth about the universe!]

But, to humanity’s shock, the message was accompanied by a devastating attack from the other civilization...

Why did they launch a devastating attack the moment they discovered human civilization?

What is the truth about the universe?

Is the universe really just a dark forest?

[Leave your brain here. The author’s knowledge is limited, so please forgive any inaccuracies.]