"Lucifer's Hammer" by Jerry Pournelle & Larry Niven (Kindle edition) is as old as I am, literally. After seeing it named as an inspiration for so many other more recent novels in the post-apocalyptic Doomer Fiction genre, I thought it only fitting to go back and read it for the first time and publish my review.
I won't kid you; there are a lot of characters in this book, sometimes so many that it will take you a moment to recall who everyone is and why you should care about them. There is a good reason for this, however, as it serves to allow you as the reader to experience the catastrophe through the eyes of, not only a set of major characters, but also from the viewpoint of many people from different walks of life.
As the comet nears and prognostications of certain doom pour forth from apocalyptic "fire and brimstone" preachers and supermarket tabloids alike, the authorities insist it will be a near miss. The problem is that, with each new set of data, the chances of an impact event are recalculated; they start-off saying that the chances of a hit are a billion-to-one against, then they revise that number down until suddenly it's only a thousand- and some say hundreds-to-one. This uncertainty breeds a kind of slow-brewing panic that comes to be referred to as "Hammer Fever."
In the beginning, nobody goes completely crazy, but you can feel it seething below the surface. People start making excuses to take-off work and visit relatives who live away from the coasts; police officers begin to notice an up-tick in crime; a U.S. Senator quietly arranges for he, his family, and his closest staff-members to be at his ranch instead of in Washington on the day the comet is to pass (with supplies acquired under the radar by saying they're for a scheduled junket overseas in a few months); a deranged sex offender takes the final leap and murders a girl he's been spying on via telescope for months, because he's sure that the comet is about to wipe them all out anyway -- why fear arrest? Also, we follow a career criminal as he plans and executes a sophisticated string of daylight burglaries of homes emptied by families taking the impromptu vacations described above, only to quickly switch gears and try to organize some of his people to survive when the impact actually happens.
One character (though he is sure there is no danger) even buys and dehydrates a bunch of beef, buys up a bunch of expensive liquor that he can use as a barter currency, and drains his swimming pool in order to refill it with freshwater and cover it to keep leaves and dirt out. All the while, he is justifying it to himself that none of it will be a waste (he and his son will use the jerky when they go back-packing, etc.) even when the comet "doesn't hit us." He assures himself there is no danger, yet he's caught up in "Hammer Fever" just the same. And, when the worst does occur, he quickly finds himself in the midst of tragic events he hadn't had the foresight to plan around.
One complaint I have is over a rather absurd scene that depicts one guy riding the tsunami wave inland for approximately a mile on his surfboard before getting smacked into a highrise apartment building. I was actually rooting for his demise, so the scene would be over. It was that bad.
Beyond that, it was a very good read, however, and so I can definitely
see why it is considered a classic of the post-apocalyptic Doomer
Fiction genre. The first parts of the book set the backdrop and allow
you to be introduced to the characters, then the disaster itself occurs,
followed by the aftermath; much of which revolves around the ranch
belonging to Senator Jellison or "The Stronghold" as it comes to be known.
Another point of interest revolves around a mailman who, after Hammerfall (the term for when the comet hit), essentially keeps on doing his job. He claims a homestead, the owners of which were murdered, as his home and base-of-operations, and continues on carrying messages. What makes it so interesting is that, because he's the only dedicated messenger around, he is able to travel (mostly) unaccosted in a very dangerous world. Doing him any harm becomes almost sacrosanct, the way it was for traveling singers in medieval times, and he is paid for his services by the people directly -- a hot meal, a cup of now-very-precious coffee or tea, that sort of thing. He is a very small character in the scheme of things, but I found his situation very intriguing.
If you've never read "Lucifer's Hammer" (Kindle edition), I encourage you to do so. You won't be disappointed.