A brief description of the light novel Tower Defense Survival: I Defend the Whole Country Alone!:
Every twenty years, the world of Tower Defense arrives to take away people and make them participate in the survival game. You can get unimaginable rewards if you can win. You can also inflict severe damage to your country if you lose.
Pierce finds himself in this world, and sent to the Tower Defense alone, while other teams have a hundred people.
Fortunately, he awakens golden hint system. Not only can he see useful alerts, he can also discover the fatal weaknesses of his enemies. Every monster he takes down rewards him with top-tier prizes. While the other players are still struggling, he is already swinging his swords to take the lives of gods.