How safe are non-combat hideouts?

[Praevasc]

As the number of facilities is really huge, it's even more sensible to have some bases dedicated only for storage/research/manufacturing. They won't launch any interceptors, and maybe won't even launch troop carriers.
However, how safe are these from enemy retaliation?
Are there significant differences from vanilla, where enemy retaliation always targeted bases which launched a fighter which shot down a UFO, but had a random chance to target another base instead. (strangely, on lower difficulties the chance to target a different base was higher, so research-only bases were more risky at low difficulty levels)

[HT]

As long as you have a garrison, they should be fine, as otherwise the first enemy attack will destroy that base. As far as  I know this mod doesn't have base-destroying enemy craft yet like missiles, so it uses mostly vanilla rules.

[krautbernd]

As long as you have a garrison, they should be fine, as otherwise the first enemy attack will destroy that base. As far as  I know this mod doesn't have base-destroying enemy craft yet like missiles, so it uses mostly vanilla rules.

As far as I can tell that literally has got nothing to do with OP's question. OP asked if bases will get attacked due to retaliation even if the base in question does not launch interceptors/attacks UFOs.

Having a garrison does not prevent reataliation, nor does it automatically prevent losing the base (if you lose the mission).

What I have been able to find regarding retaliation missions:

The 3 last regions don't have any random missions assigned and they won't see any Alien Terror missions since they have no cities present. However, it will be possible to see Alien Retaliation missions if any UFOs are shot down over those areas. This is because the target region for the retaliation is randomly picked between the UFO's mission region and the intercepting craft's point of origin. In the event that the interceptor's point of origin was one of these regions, a nearby region may be substituted in. Original handling would default the region to North America.

https://www.ufopaedia.org/index.php/Alien_Missions_in_Enemy_Unknown_(OpenXcom)

According to Hobbes the detection chance is:

[...] is given by the formula: (completedFacilities / 6 + 15) / (mindShields + 1)

https://openxcom.org/forum/index.php?topic=6380.0

Hence retaliation missions can (hypothetically) "target" any of your bases if they happen to be in the mission region or the region the interceptor originated from (provided I understand the article correctly).

[Praevasc]

Hence retaliation missions can (hypothetically) "target" any of your bases if they happen to be in the mission region or the region the interceptor originated from (provided I understand the article correctly).

Thanks!
So, it seems in order to eliminate the risk of a base getting attacked, we should place it far away from the busy regions, and don't shoot down UFOs near it, even if the interceptor comes from a different base.
It seems then, that the South Pole would make a great research base. (I did it back in the day with vanilla, and never got attacked)

Putting it next to the main base, to reduce transfer times and costs seems to be a bad idea then, because UFOs target the region, not the base. Too bad I just did so in my current campaign. 

[krautbernd]

Thanks!
So, it seems in order to eliminate the risk of a base getting attacked, we should place it far away from the busy regions, and don't shoot down UFOs near it, even if the interceptor comes from a different base.

Going by my own experience there is no way to "eliminate" the risk. You can only reduce it. I've had new bases attacked (and destroyed) that have never housed any soldiers or crafts and which were located in entirely different regions. The Ufos just happended to be flying over them on the way to the target region.

Don't ever assume that your bases are immune to attacks only because they are located in remote regions. You are just asking for trouble. Never leave your bases totally undefended. Remember, all it takes is a single Battelship that you might not even detect and that base is gone.

[Praevasc]

What makes this issue even more critical, is that a larger number of bases seems to become necessary, as the number of facilities is significantly larger than in vanilla, yet the base has the same number of squares.

[krautbernd]

On the other hand you can actually cut down on some facilities which have larger versions (living quarters, workshop, stores), hyperwave decoder still makes radars obsolete, base defenses are still pretty useless (unless built in impractical large numbers). Other facilities actually combine multiple functions (HQ). Manufacturing bases aren't really a thing anymore (at least for me), as you can't manufacture stuff for profit anymore due to balancing. Also the number of scientists you are able to use is drastically reduced due to limited research facilities with vastly lower research space. In vanilla one laboratory = one living quarter, here it's more like one living quarter per three research facilities.

Similarily I'd say that X-Com animals aren't needed (I find them quite useless tbh) and alien containment/prison facilities kind of flow into each other (meaning you probably need multiple prisons in the early game, and multiple containment facilities in the late game). They become redundant as you work your way through the interrogations. I also found myself needing multiple gyms per base in earlier versions, with how max stats are currently you can probably squeeze by with one.

Then again I also my recruitment office submod to streamline agent vetting and I have also upped the limits on prisons&containments for convenience.

I still find that base numbers are dictated more by UFO detection (and craft range/speed) rather than by limited space.

[Tchey]

Hello,

Is it then possible to "win" the game with only one base and never a second one ?

[Mrvex]

Hello,

Is it then possible to "win" the game with only one base and never a second one ?

Probably yes, but it will be very hard both on gameplay AND mainly your sanity, without additional bases you will struggle with storage capacity and you might also not be able to have alot of hangars to be able to send troops to multiple places at once so you will be forced to excell in every single mission you do get.

Having multiple bases is intended and how you should play. The ability to respond to multiple missions at once is also important and until you get something like a Skyranger, your crafts might not be even able to get to ther destination if for example your base is in Athens, Greece and there is Alien Terror in Rio De Janero.
And some cults only operate in certain regions, like Exalt in USA.