War Core, Book 1: Hold the Line (a LitRPG, RTS, Dungeon Core Adventure)

Book excerpt: Earth is under siege. For decades, the governments of our world have been fighting a desperate and secret battle to keep hordes of alien invaders away from our planet. When the guardian of the United States falls, a new champion must be chosen. Sadly, the choice of a champion isn't ours to make, and the Galactic Conflict Authority selects a human, seemingly at random, to lead the United States of America's efforts at holding back the tide. Hugh Logan is in the middle of teaching a class when he is taken against his will and informed that he is now the newest member of Earth's defense against alien invasion. He must give up everything to become our champion. He must give up everything to prevent our destruction. He must become... a War Core. War Core is a Dungeon Core series with LitRPG and RTS elements.