So far from my playthrough Surviving the Aftermath is a decent city builder.
Above your city map there's a Frostpunk-like overmap in which you can send "specialists" to explore , loot and scavenge location for items or research points or fight bandit camps or move the background storyline forward.
Similarly to Surviving Mars you sometime get disasters coming , on my town i got some radioactive cloud, an attack of mutated spider/tick-like creature and currently a freezing wintery wave a la Frostpunk (though nowhere near the difficulty of that game)
There are events too, like some survivors, merchants etc... coming to visit and trading, children grow up into adult to join your workforce, there are lot of researches to do to improve productivity, buildings or unlock new buildings...
you get people getting hurt, irradiated , diseased, mutated, hungry, dehydrated etc.. due to various circumstances but various buildings can help or heal them to not dying, though dying from old age is a thing in that game.
Now maybe it's because for my first learning playthrough i set all the difficulty settings to low but so far it feels a bit too easy to overcome those challenges coming your way (Surviving Mars had that problem even when increasing the difficulty a lot), but it will certainly get better once i'll go to my next playthrough with higher difficulty setup, but that's nowhere close to Frostpunk for the survival challenge difficulty so far.
There's some good potential for people that like this genre, hopefully it will not be a wasted potential in the end