If the Earth was actually hit by a CME we'd know a few days in advance. It would mostly take GPS (any satellite-based technology, really) and the internet down, but power plants would be able to be shut down beforehand so most of the really bad damage could be avoided.
At the risk of sounding like a Kotaku writer, the game is like a mixture of Fallout and Metro 2033. The gameplay is similar to FO1 and 2 but the world is closer to Metro with everybody living a big underground train station. It's one of my favorite takes on the post-apocalypse, people don't talk about what happened regularly like it was a recent event. In fact, nobody ever talks about what happened or why they all live underground. The way they live is normal to them, you never find out what the horrible world-ending scenario was and most people are completely unaware such a thing happened. Speaking of Metro..
>Metro 2033 and others
The series is a little hit or miss for most people, it has its flaws but there's nothing like playing a Russian FPS and all it entails. Exodus is different to the first two, having a set of linear levels mixed with semi-open world areas that are vaguely similar to STALKER. I know people who don't like 2033 or Last Light, but do like Exodus and visa versa.
A weird pick, but the games often point towards it being set after some kind of horrible catastrophe that wiped out humans. The upcoming game is the most direct about this, being set in an overgrown abandoned city.
Probably the best zombie game out there that isn't Left 4 Dead. At the surface it seems like your standard indie crafting survival game, but what sets it apart is how mechanically in-depth it is and how lived in the world is. The game is set in a gigantic map with several life-sized towns, entire neighborhoods with houses that are all fully furnished and stocked with random junk you'd expect to find in a house. You can enter any random house and find silverware in the drawers, tools in the shed, bookshelves with readable books, food in the cupboard, clothes in the wardrobes, etc. If you want you can go innawoods, forget society and turn the game into Farmville by growing your own crops and living in a shack you build in the middle of nowhere. The only game I've played in its genre that truly feels like you're a savager trying to navigate the end of the world.
From the legendary Gothic developer Piranha Bytes comes a game that can only be described as pure Eurojank. Heavily exploration-focused, unorthodox but interesting gameplay ideas, mechanically rich, highly divisive and clunky as hell. A true European RPG. If you're in the mood for something that's kind of awkward but breaks the formulaic mold of AAA games like Far Cry 6 and Cyberpunk 2077, give it a try. There's a sequel that might smooth out some of its more jagged edges, if you prefer waiting.
Classic Slavjank; ugly, buggy, barely functioning yet incredibly fun and in-depth. Commonly considered to be Soviet Fallout, ATOM RPG takes heavily from CRPGs classics such as Balder's Gate and the aforementioned Fallout. If you know anything about those games, you already know how ATOM RPG plays and functions. In fact it feels more like a Fallout fan game than it does its own IP, right down to the UI. Still, if you like those kinds of games you'd probably enjoy it.