Rebirth of the Thief Who Roamed the World

From the introduction:

Yes, this is a world many years into the future of what you know, a world with interstellar travel, mechs being used in the military… and a very, extraordinarily advanced Virtual Reality setup.

So advanced that the rest kinda doesn’t matter very much. This is a world where the game Conviction has gripped the human psyche like a vice, becoming not just a game but a second world for humanity, where they can shed the bounds of mundanity and be wizards and warriors, soar through the skies on their mounts or spend their days hunting ghouls and treasure in deep dungeons.