The Black Sun — Andrei Livadny

Zander and his gamer friends used to face danger without fear, finding strength in the promise of a safe respawn. Nothing could harm or destroy them. This was only a game ... or was it? A game, played in an ancient hyperspace network. A game involving dozens of real-life alien civilizations. Earth is deserted. The fate of humanity is unknown. The few human survivors are now stuck in the Darg star system. All they can do is fight to the last. They must find the Phantom Server-the nucleus of the interstellar network created by the ancient civilization of the Founders. In order to live, they must solve its mystery or die trying.