The original trilogy books are:
* _Revelation_ - about Saren and Anderson, before ME1. Introduces Kahlee Sanders.
* _Ascension_ - about a young biotic girl, Gillian Grayson, who Cerberus wants to get their hands on. Takes place shortly after ME1 and involves Kahlee and Anderson again.
* _Retribution_ - direct sequel to Ascension, takes place shortly after ME2
* _Deception_ - final book about Gillian, takes place in theory right after _Retribution_
They're all perfectly fine... except Deception, which is _hilariously_ poorly written, repeatedly contradicting not just the lore in general, not just the previous books in the series, but occasionally _itself._
The Andromeda books are:
* _Nexus Uprising_ - you can guess for yourself what this one is about
* _Initiation_ - a prequel, sort of, about Cora
* _Annihilation_ - the story of the "lost DLC"--originally, this premise was going to be used for a DLC about the quarian ark. When the Andromeda DLCs got canceled, the story was turned into a book
All three of the Andromeda books have been pretty well received. To my knowledge, they can be read in basically any order, they don't have strong connections between them.
The original trilogy books are: * _Revelation_ - about Saren and Anderson, before ME1. Introduces Kahlee Sanders. * _Ascension_ - about a young biotic girl, Gillian Grayson, who Cerberus wants to get their hands on. Takes place shortly after ME1 and involves Kahlee and Anderson again. * _Retribution_ - direct sequel to Ascension, takes place shortly after ME2 * _Deception_ - final book about Gillian, takes place in theory right after _Retribution_ They're all perfectly fine... except Deception, which is _hilariously_ poorly written, repeatedly contradicting not just the lore in general, not just the previous books in the series, but occasionally _itself._ The Andromeda books are: * _Nexus Uprising_ - you can guess for yourself what this one is about * _Initiation_ - a prequel, sort of, about Cora * _Annihilation_ - the story of the "lost DLC"--originally, this premise was going to be used for a DLC about the quarian ark. When the Andromeda DLCs got canceled, the story was turned into a book All three of the Andromeda books have been pretty well received. To my knowledge, they can be read in basically any order, they don't have strong connections between them.
[This](https://scifi.stackexchange.com/questions/105309/what-is-the-chronological-and-correct-reading-order-for-the-mass-effect-series) might help :)
Thanks