The plot was something along the lines of MC being poor and only option was succeeding in this (probably blackmarket type) vr game where he couldn't move his body so something along the lines of "if I don't succeed in... My body will do of heatstroke" as he locked himself into a motel while playing the game. The game itself seemed to be him infiltrating a castle or tower or something and slowly getting my abilities but always having to be scrappy and sneaky like. Remember him crafting most of his own gear by cobbling together random shit he got from loot drops. Book was most likely from kindle unlimited