"Gatecrashing" is an add-on to ground breaking Eclipse Phase and it lives up the usual high standard for the rest of the line. It expands the already rich setting beyond solar system and into bizarre alien worlds accessible through the mysterious Pandora Gates.
The main section has in-depth description of two score gate destinations chosen according to their relevance to Firewall for their X-risk potential. Most lead to planets that were visited by ET post-singularity civilisations that have long since gone extinct. Unlike the majority of sci-fi, in Eclipse Phase the alien planets are truly alien with only a handful earth-like planets habitable to unmodified human life. Every destination has a mystery to solve and a few story seeds for the GM.
The rest of the book deals with gatecrashing operations and possible ways for the PC's to get involved as well as a smattering of new equipment and morphs. There is a guide for creating believable custom planets that will come in handy for any GM that wishes to expand the EP universe.
In my humble opinion "Gatecrashing" is the best product so far in already high quality EP line and I highly recommend it to anyone interested in sci-fi. Solid A from me.