Oh ♥♥♥♥, Archipelago for XCOM2? Wild.
For a quick primer: Archipelago is a form of randomiser with a scope far beyond the traditional single-game version. Instead, it takes the randomisation of two or more players, Player 1 and Player 2, and combines both sets of items/research/whatever into a single multiworld. (Archipelago is entirely playable single player, but I'm discussing its wider scope, so we will focus on the multiplayer aspect.)

Essentially, Objectives completed by a Player give random research projects/shadow chamber projects, but these can belong to either player. Player 1 may find their own muton autopsy after Gatecrasher, or they may find the plasma rifle research for Player 2. Both games of XCOM2 are being played, each player having access to whatever is found corresponding to their game, thus allowing for a sort of multiplayer game to occur despite both players playing their own separate XCOM2 campaign. EDIT: Shoutout to AHHH REPTAR two posts below for having a better grounding and being able to explain to me what's currently being randomised.

Archipelago goes further than just a single game, however. Its full concept is one of a multi-game multiworld, where Player 1 may be playing Castlevania, but Player 2 could be playing The Legend of Zelda, or Pokemon Emerald, or any of the games on the supported list.[archipelago.gg] So Player 1 in Castlevania might find an item, but instead of it being a Castlevania weapon, it's a Legend of Zelda weapon for Player 2, and vice versa. After all, once both games are randomised, aren't the item packages being randomised simply unlock pickups that can be transferred as data packages to each other?

EDIT2: As pointed out two posts below, XCOM2 is unsupported, meaning that this is a work-in-progress mod by members of the Archipelago community, who will be willing to play games that are not officially listed, but also have this capacity. Also provided: a link to a full list of in-progress/completed unofficial archipelago multiworld games[multiworld.news] that would also be playable.

It's a fascinating way to think about game architecture, but I digress. I am unclear how exactly this will work for XCOM2, but similar concepts have been carried into all sorts of games. This mod is ambitious and a lot of work, but it may be an incredible experience for people who have an interest in randomisers, a collection of friends and a wide interest in games.

This is clear that it is a very early test release and may not work. All of the mechanics involved, how items are transferred for xcom2 specifically etc etc. is presumably still a work in progress and at the purview of the modder/programmer. I, for one, will look forward to updates patiently and willing to let the programmers work out how they want to do this, because I think it could be a great experience.