Love them or hate them there are a lot of common tropes across the science fiction genre. What are some of your favorite and least favorite tropes?
I think it goes without saying that one of the least favorite tropes is Deux ex Machina. I couldn't quite put my finger on it at first, but after watching the German TV show "Dark" I was utterly dissatisfied with it. The entire series up until the very last episode is about this inescapable time loop and alternative universes which is pretty cool while watching it, but then you get closer and closer to the end wondering how they are going to solve this impossible problem. Then surprise they just do it instantly in the last episode.
Another trope I am not very fond of is nanotechnology where there are trillions of tiny robots that can effectively act as magic. It just feels like a lazy way to write science fiction because you really want a fantasy.
A trope I do actually like despite how overdone it is, is the idea of a precursor or forerunner. It often brings to light the absolutely massive scale of the universe which I find fun to think about.
It's a common theme where humans encounter some structure or evidence to suggest that some species or alien had existed millions or billions of years prior to humans. In Halo there are the forerunners that built the Halos for example. If you've ever played Mass Effect there are the mass relay's that humanity and other alien species discovered that connected large parts of the galaxy.
This concept drives me insane, because I also love it but my favorite example is one that both heavily plays with it, but also 85% of the book relies on you not knowing it's coming.
Like Earth All Along is almost always a spoiler, but this one just hits exactly right for me.
(Or, more simply -- "Where I come from, we call it a Faraday Cage.")