It is the distant future and the human race has gone. Whether extinct or moved on to a higher level of existence, nobody knows. Their civilization has been inherited by the cybertanks: massive atomic powered war machines with mentalities modeled on the human psyche.
The 2nd book in the Thrilling old Guy/Cybertank Adventures!
In the distant future mankind creates sentient cybertanks patterned on the human brain to help fight their alien enemies. Then, inexplicably, the humans vanished. They just went away. All that is left of the human empire are the cybertanks who, in their own way, keep the human civilization alive.
Old Guy rides again! The fourth in a series of thrilling Old Guy/Cybertank adventures sees Old Guy off on some exciting new adventures. Everyone's favorite near obsolete weapon of mass destruction returns with some old, and new, friends in more great stories in the style of Chronicles of Old Guy.
I'm not sure if I want to know more about the location backstory, or see where this tale is leading to in the future. Either direction in time is good. This guy can write, and has some fiendish ideas as well!