This game takes place in a world in which the humans were defeated by the aliens. XCOM is now a renegade organization that travels the globe, seeking to uncover dastardly deeds done by the aliens and their human collaborators.
Once again, it's a turn-based strategy game that boils down to placement of units, timing, squad cohesion and making use of individual classes. Differences between classes have been accentuated so that, for example, rangers have more melee skill, while snipers have extra pistol slinging capabilities.
Maps are, to some extent, procedurally generated, so each time you drop in, aliens and props will be in different places. There's also a greater emphasis on stealth, so players can take the time to get into the best position before launching an attack.
Once again, the individual soldiers have a great deal of value. As you upgrade and personalize each of them, so the pressure increases to keep your favorites alive. Once they're dead, they're dead. The only consolation is that you can visit an HQ place of memorial to pay your respects, and maybe to say sorry for placing them in dire straits.
Meanwhile, publisher 2K Games today announced a DLC "Reinforcement Pack" that the company says offers "new missions, aliens, weapons, more extreme soldier customizations and other items." It costs $19.99, or it comes included in the XCOM2 Digital Deluxe Edition, which also includes a soundtrack and costs $74.99.