[Feature Request] Campaign Mode with a shared base

[TheYellowArchitect]

This mod revived my excitement for XCOM, as I have finished every game in the franchise, and while overhaul mods look exciting, they were never hype enough for me to pre-invest a week for finishing them. This mod, however, allowing me to play with a friend we play co-op games together, made me return to XCOM 💛

However, he is unfamiliar with XCOM: UFO Defense and it will be overwhelming for him, so the idea is to assign all the Geoscape part to me, or at least, most of it. Basically, to have 1 base, instead of 2.

What makes this feature also beneficial, is that overhaul mods like: X-Com Files, and UNEXCOM start with scripted, story-based missions.

X-Com Files makes Co-Op especially attractive because it starts with 2 agents, 1 for each player. So it serves as a good combat tutorial, and good scaling instead of starting with a full squad.

But by having 2 bases, the above advantage is lost, as bases and agents and funding and items are duplicated. Basically, duplicate bases helps for sandbox experience (UFO Defense, TFTD), while some mods benefit from this optional feature.

I also think I'm not alone in seeing the usefulness of this feature as I saw today another player on the Discord server requesting it.

I know this is a big feature, so at least, if the geoscape difficulty remains the same (e.g. enemy activity is not increased), a good workaround and quick-implementation, would be to "demolish/destroy" the 2nd player's base automatically. I assume OXCE provides such functionality. Even the base game indirectly had a "demolish/destroy base" if a base defense mission was lost so I assume this is implemented in OXCE.

[TheYellowArchitect]

https://www.moddb.com/mods/openxcom-coop-mod/downloads/openxcom-co-op-mod-v170-full-release

Changelog 2026/03/30
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4. It is now possible for a player to join a campaign directly from the main menu (New Battle), without needing a save file. The joining player cannot access their own bases or crafts, and cannot purchase items or equip soldiers while in a teammate’s base, but can still take part in Battlescape missions. In Battlescape, the host can give soldiers to a teammate. If the connection is lost, the joining player is returned to the main menu. Please note that this feature is still a work in progress and may change later.

I would close this issue as it seems you have already implemented the workaround/quick-implementation (thank you so so much), but I will keep this issue open because it's about sharing a base so both players use the same resources in a base. So the new player slowly browses base stuff and learns slowly while the other player is in the Geoscape, instead of doing nothing.

Anyway, since this is basically implemented, and the above paragraph is daydreaming (16-players sharing a base, soon?), I think this issue is low-priority, as it's less beneficial implementing, compared to 4-bases in geoscape by 4 players, or having 2~4 players in battlescape playing simultaneously instead of linearly.

[TheYellowArchitect]

Re-opening it because I realize this is basically a regression bugfix of this feature implemented in 1.7.0 and makes the base column of #15 not so important, as this feature/regression bugfix is a workaround for it (since if fixed, you can join XCOM both with shared base, or duplicate base)

[xcomcoopdev]

This feature is not enabled by default in versions newer than v1.7.0. In v1.8.4, go to Options → Multiplayer and make sure that “Only Host Can Save Each Player’s Progress” is disabled. It then works the same way as in v1.7.0.

This feature still needs some improvements. Right now, the client cannot do anything in the host’s base. If I understand correctly, you want both players to be able to use the same resources in a shared base. Who creates a new base? Would either player be able to access the crafts, soldiers, facilities, and so on?

I understand that there is a need to start a new co-op campaign with only one shared base. We can look at this again after most bugs have been resolved.

I do not think this is impossible to implement, but it will take time.

[TheYellowArchitect]

This feature is not enabled by default in versions newer than v1.7.0. In v1.8.4, go to Options → Multiplayer and make sure that “Only Host Can Save Each Player’s Progress” is disabled. It then works the same way as in v1.7.0.

I can confirm it works. I am surprised to see it, and also happy :)
I understand it needs improvement as the other player is basically without a geoscape. He doesn't even have P1's geoscape events popup, nor can he do anything in the base.

If I understand correctly, you want both players to be able to use the same resources in a shared base. Who creates a new base? Would either player be able to access the crafts, soldiers, facilities, and so on?

Ideally yes, but this is such a big feature, and honestly, simultaneous co-op battlescape is a far better investment of time than this feature. I suggest somehow enabling this feature for the few that want it (as it's now hidden behind a seemingly unrelated bool flag in options) until this feature has much added to it, whenever that time is. With a disclaimer/tooltip that the entire Geoscape is missing for the non-shared base player, but Battlescape works fully.

If shared-base was to be expanded, these are what I would consider minimum features for it to be considered complete:

1. Bases button in Geoscape, instead of doing nothing -> Opens the other player's base, just like clicking into the player base from the Geoscape
2. Base menu, having the Agents button, and the few features related to that sub-menu (renaming them, adding armor to them)
3. Remove 'Build New Base' button from shared base
4. P2 (non-base-player) at start of battle, right before the battlescape, can change the loadout of agents.

Everything atop of that is extra. E.g. seeing Research or assigning Research, or selling items or purchasing items.
I see only the above 4 as essential to a shared base playthrough (renaming ftw for tagging soldiers to each player, instead of implementing agent ownership)

I understand that there is a need to start a new co-op campaign with only one shared base. We can look at this again after most bugs have been resolved.

I fully agree. It's a minor feature and it's kinda implemented already. And if a big new feature is to be added, simultaneous battlescape (especially with e.g. 4 players), imo is more fun than this