Snowpiercer is about a train where the last remnants of humanity live during an ice age. Which is a really goofy premise, but you kinda end up buying into it pretty quickly. It’s not quite as good as I’d hoped, but it’s pretty good.
It’s a whole social commentary sorta thing, where the back of the train is inhabited by the dirty poor, while the front is douchey rich people. And of course the poor people in the back get pissed off and want to take over the train. Chris Evans is the leader of the poor people. Tilda Swinton is great but almost unrecognizable as the front-of-the-train person who disciplines the poor people. John Hurt, Jaime Bell, Ed Harris, and some Korean people I don’t know are also in it.
I never got any idea as to why they’d use a moving train at all. Briefly, I thought the train might go fast enough to chase the sun and stay in daylight all the time, but that doesn’t seem to be the case. It’s a train that runs at more or less regular train speed forever. But if they have an engine that is effectively a perpetual motion machine, it seems like it’d be much easier to turn that into a generator/heater for a stationary fortress than a moving train. But ultimately I think they just liked the train aesthetic and didn’t care that much for whether it made any sense.