Project Hail Mary by Andy Weir is one of the easiest modern science fiction books to recommend because it combines problem solving, humor, isolation, friendship, and high stakes. If you finished it quickly, the next book should preserve at least one of those pleasures instead of only matching the space setting.
Read The Martian for more Andy Weir
The most direct next read is The Martian. It has the same practical problem-solving energy, the same readable science voice, and the same interest in surviving impossible conditions one step at a time. The tone is more survival-log than cosmic mystery, but the appeal is very close.
Read The Martian if what you loved most was competence: a smart character facing a chain of technical problems and solving them under pressure. It is also a strong choice for readers who want science fiction without a heavy learning curve.
Choose All Systems Red for voice and speed
All Systems Red by Martha Wells is shorter and sharper, with a very different protagonist. It is a good follow-up if you liked the humor and emotional surprise in Project Hail Mary but want something faster and more character-driven.
The Murderbot books are useful for readers who want science fiction that moves quickly without feeling thin. They combine action, anxiety, corporate critique, and a voice that is immediately recognizable.
Go bigger with The Three-Body Problem
If you liked the civilization-level stakes in Project Hail Mary, try The Three-Body Problem by Cixin Liu. It is less cozy, less funny, and more conceptually severe, but it expands the scale of first-contact science fiction.
This is a better next read for people who want big ideas more than banter. Expect mystery, physics, history, and a colder sense of cosmic risk.
Try classic scale with Dune or Foundation
Dune and Foundation are not tonal matches for Project Hail Mary, but they are useful if Andy Weir made you want more science fiction as a genre. Dune gives you politics, ecology, and religion on a desert planet. Foundation gives you empire, history, and long-range planning.
Choose Dune if you want world-building. Choose Foundation if you want civilization-scale ideas. Choose neither if what you want right now is the same friendly momentum as Project Hail Mary.
Build the right path
A practical reading path is The Martian, then All Systems Red, then The Three-Body Problem. This moves from similar voice and problem solving into faster character sci-fi, then into larger first-contact ideas. After that, use Sci-Fi and Space on Bookble to branch by mood.
The key is to decide what you want to repeat. If it is science puzzles, stay with Andy Weir. If it is emotional surprise, try Murderbot. If it is cosmic scale, move toward Cixin Liu. Project Hail Mary is a doorway, and the best next read depends on which part of the doorway you walked through.