Insignia, book 1S. J. Kincaid2012

More than anything, Tom Raines wants to be important, though his shadowy life is anything but that. For years, Tom's drifted from casino to casino with his unlucky gambler of a dad, gaming for their survival. Keeping a roof over their heads depends on a careful combination of skill, luck, con artistry, and staying invisible.

Then one day, Tom stops being invisible. Someone's been watching his virtual-reality prowess, and he's offered the incredible?a place at the Pentagonal Spire, an elite military academy. There, Tom's instincts for combat will be put to the test and if he passes, he'll become a member of the Intrasolar Forces, helping to lead his country to victory in World War III. Finally, he'll be someone important: a superhuman war machine with the tech skills that every virtual-reality warrior dreams of. Life at the Spire holds everything that Tom's always wanted friends, the possibility of a girlfriend, and a life where his every action matters but what will it cost him?