Okay, so admittedly, I haven’t actually read that much adult scifi. I really only started really getting into in this year. Maybe, though, my lack of experience makes me a good source for recommendations! (Or maybe not. Whatever, you’re getting recommendations anyway, people.)
One thing you have to understand about adult scifi (or actually, just adult SFF in general) is that it's often very slow to start. Up to the first quarter might just be about setting up the world and making sure you understand the general rules of the setting. Obviously, this isn't the case with every book, but many of the ones I've read so far have seemed like this.
Anyway, out of the adult scifi reads that I have read, there have definitely been some great ones- hence this post. Onto the recommendations!
The Martian by Andy Weir
Mankind sends a mission to Mars. The mission goes wrong and one man is left behind. This book is about that man's struggle to survive on a planet with limited supplies and almost no one to help him. This is a very science heavy book, but it's also balanced with a lot of character development and humour, so I think mostly the science wasn't too heavy handed.
Parasite by Mira Grant
This book is scarily realistic and the twists are amazing and the characters are so well developed (especially Nathan. Love him). Basically, there's this tablet that people take, which contains a tapeworm which then grows in your body and controls your organ systems so that you never get sick- no more medical conditions, no more medications, just complete healthiness. Or is there something else going on....
I've heard Feed by the same author is pretty good too!
Hyperion by Dan Simmons
Told in 5 parts- each of the tales of each of the passengers on a flight to the planet Hyperion- this book was one of my first of the adult scifi genre, and it's truly fantastic. A bit slow to start for each of the tales, but there's a point in each of the parts where the pace explodes, and you struggle to put the book down.
The Hitchhiker's Guide to the Galaxy by Douglas Adams
Humour, Adventures (sort of)
This book (and actually the series overall) is hilarious. It's such a dry humour, you can't help but laugh. If you've seen the movie, I'm sure you know what I'm talking about. If you haven't seen the movie or read the book, you need to do at least one of those things.
Fortune's Pawn by Rachel Bach
This book is very romance heavy, so might be a good one to start with if you're not really used to big scifi focused books.
Cloud Atlas by David Mitchell
Every Genre Ever
The idea behind this story is such a clever one. It's split into 11 sections, with a total of 6 narrators, with the first 6 sections being narrators 1-6, then the last 5 sections being narrators 1-5 but in reverse order. (So the sections were: N1, N2, N3, N4, N5, N6, N5, N4, N3, N2, N1; N = narrator). The sections for narrators 1-5 were each telling half the story, so the first five sections were sort of cut off with cliffhangers (and then wrapped up later in the book). Each section is very different, ranging from historical to contemporary to science fiction, with different narrative styles and structures.
Ready Player One by Ernest Kline
Virtual Reality, Adventure
This book has YA/A crossover appeal, since the main character is quite young. If you're any sort of fan of 80s/90s pop culture, or gaming, this is definitely a book for you. Honestly, I didn't get a lot of the references made (probs a bit young to pick up on them all) but I still loved the book. AND YOU WILL TOO. :P
Do you read a lot of adult sci-fi? Any recommendations for me?