Dead Mech Walking: a Mech LitRPG novel - Armored Souls, #1

100 tons of walking steel. One human heart. Sgt. Reggie King wakes up from a battlefield injury to find himself physically intact. But the hospital staff insist he's not fit to return to duty. As part of his psychological recovery, they introduce him to a game. Armored Souls is a tank game on steroids. Giant, walking mechs called juggernauts engage in interplanetary wars as noble houses and mercenary factions wage endless battles for supremacy.
For the pilots of these juggernauts, the rewards are glory, cash, and XP. As a tanker in real life, Reggie has a leg up on tactics and leadership, but he's got a lot to learn in the game world. Saddled with trigger-happy commanding officers, slacker teammates, and bafflingly incompetent NPC underlings, Reggie will have to struggle to make headway. Meanwhile, a sinister player decides to make Reggie's life hell after their two factions clash.
Reggie is forced to find a solution to his griefer problems while battling the real life demons that chased him into the game in the first place..and they won't let him quit.