The City of Ember (2003)
The People of Sparks (2004)

The builders of Ember are retarded, they deprived the vault dwellers of any ye olde knowledge but still think that they would survive in the wastelands after one way trip through the river. What if it is winter there? How megapolis type folk are supposed to instantly became farmers, when they don’t even know what sun is or what trees are.

Otherwise, the first book is OK by itself, but i can’t remember anything from the movie. It was something-something retro-futurism art-deco and not ye olde and raggedy enough. It bombed similarly to Golden Compass but unlike that, its second book is plain war and xenophobia are bad mmkay, where in His Dark Materials stuff got only crazier. Well, overall, the sequel teaches kids to speak to adults, and to avoid unforeseen consequences. It’s mildly entertaining so you can ignore tarded premise. First story was a self-contained tale type with the symbolic egress ending. This one picks up exactly where the story left us, and grounds the whole world by depicting realistic consequences and a realistic solution.
The Diamond of Darkhold (2008)

Hm, a post-apocalyse born grandpa used the word “slowpoke”, which was entirely seized by the Poketto Monsuta translation team. A human, who still remembers it as is won’t survive the apocalypse, well, rather soon they will all die from old age in the real life (the book is written in 2008). And the word “slowpoke” after resurfacing with the same meaning due to the popularity of Poketto Monsuta franchise, has already morphed into just “slow” (noun).

The story suffers from poetically retarded humanities — they made only one trip to salvage some stuff from the city, instead of utterly ransacking it. The could take all the lights, all the houses, all the wires and floodlights into their village. What retard would leave generator parts behind? Or so much pipework? Any way that is pure extracted and already refined metal, ready to be re-used.

And that’s in case of not re-habituating it for winters, and just making new fields outside, with new wiring from the solar…
So all this time the builders had extremely effective solar generators, which could be repaired from inside the city, with some lift-thing, but instead they’ve built an ancient weak generator, which was failing and degrading, as a main energy source? City of Ember should never had sequels. In a way, the fact that there is no second, third (especially third) or fourth movies after the City of Ember is a good thing (unlike His Dark Materials). It keeps the story clean and self-sufficient. It doesn’t plug some holes by creating other ones.

And the aliens subplot is not developed beyond declaration of its existence.