Tomorrow's War: Awakening

The protagonist accidentally travels to the year 2155 and discovers that technology there is even more backward than it was in 2010. The cause is the abuse of certain technologies, which led to a massive technological regression. What's more, species that once existed on Earth have all returned, mutated and become incredibly ferocious. To survive, humanity has built several enormous shelters and constructed thick walls to fend off attacks from these savage beasts.

This novel and its characters are entirely fictional. Any resemblance to real people or events is purely coincidental. Do not imitate.