BASE DEFENCES

[SIMON BAILIE]

On previous games I've noticed the following: With 3 fusion ball defences and a grav shield I shud only have to hit an attacking battleship 3 out of 6 times which I've number crunched to a 98.3%, so by that stage in ur game it's unlikely u'll have to do a base defence mission. My query is this, is the amount of damage done by base defences variable and if so in what way? But under these circumstances, if fusion ball defences r fixed @ 1200 damage why sometimes does it only takes 2 hits to destroy a battleship and on the other extreme 4 hits. I've no screenshots or saves with this in it, if I come across this again I'll certainly upload them. Also apologies if this is the wrong section for this query as I couldn't think of anywhere else.

[Meridian]

1200 is the base damage.
Damage range is 50 to 150%, i.e. 600 to 1800.

It was not like that in v1.0 yet, but it was fixed in August 2014: https://github.com/SupSuper/OpenXcom/commit/7ccb87731add003a866bade8b2dea92f337e53b3

[SIMON BAILIE]

Ta, so in theory u might need to hit all 6 times with fb defences which number crunches to a 26.2%. I suppose it's a way of keeping the possibilty of having to do a base defence mission higher than roughly 1 time for every 60 attacking battleships!

[hellrazor]

Ta, so in theory u might need to hit all 6 times with fb defences which number crunches to a 26.2%. I suppose it's a way of keeping the possibilty of having to do a base defence mission higher than roughly 1 time for every 60 attacking battleships!

Base defenses installations are actually useless. It's better to get rid of the retaliationmission with a base defense mission, i usually skip them totally. Mindshields are the way go.

[Meridian]

There is no way to totally prevent base defense missions:

1. Even though there is a minimum damage (600) for fusion ball defences, they also have only 80% hit ratio, so if you are unlucky, they can miss even 1000 times in a row.

2. Mind shields are also not 100% effective. One does a really good job, two do an amazing job (yes, they do stack in OpenXcom!)... but there is always a small chance aliens will find your base.

3. A funny option (which you can see in my Hawaii Challenge LP on YouTube) is also not to shoot down UFOs at all. That way alien retaliation missions will not be generated in early and mid game (each time you shoot down a UFO, there is a small chance of retaliation mission spawning). But late game, they can be generated even without shooting down UFOs.

My recommendation:
- don't shoot too many UFOs down early in the game (you want them to land anyway, and raid them for Elerium)
- build 1 mind shield in every base; 2 if you're rich and have place to build
- don't bother with defences/gravshield... do the defense mission and everything resets again

PS: if you really want defences then 5 plasma+grav shield or 4 fusion ball+grav shield is the minimum... otherwise you'll not shoot them down effectively enough (i.e. you'll have to play base defense mission cca once for every 10 alien attempts)

[hellrazor]

2. Mind shields are also not 100% effective. One does a really good job, two do an amazing job (yes, they do stack in OpenXcom!)... but there is always a small chance aliens will find your base.

I didn't know that hey would even stack, nice!!

My recommendation:
- don't shoot too many UFOs down early in the game (you want them to land anyway, and raid them for Elerium)
- build 1 mind shield in every base; 2 if you're rich and have place to build
- don't bother with defences/gravshield... do the defense mission and everything resets again

PS: if you really want defences then 5 plasma+grav shield or 4 fusion ball+grav shield is the minimum... otherwise you'll not shoot them down effectively enough (i.e. you'll have to play base defense mission cca once for every 10 alien attempts)

I concur totally :Y

[SIMON BAILIE]

2. Mind shields are also not 100% effective. One does a really good job, two do an amazing job (yes, they do stack in OpenXcom!)... but there is always a small chance aliens will find your base.

So in what way do mind shields affect the chance of aliens detecting ur base. In other words since they stack is it worth having 3 or more in 1 base?

[Warboy1982]

it's a divisor

short version is:

detectionOdds = detectionOdds / (1 + numberOfMindShields)

1 is good (50%), 2 is better (33%), 3 is excessive, but probably the sweet spot in terms of bang for your buck (25%), and you won't see nearly as much of a return on a 4th (20%).

[SIMON BAILIE]

I'm quite happy with only having 1 mind shield on most of my bases, but the main research and workshop bases could do with having their detection chance minimised as far as practical. One final point as I've spent the last hour searching for it, and I can't mind where I found it b4, what is the base chance of aliens detecting ur base and if u have the "aggressive retaliation" option on does this affect it?

[Arthanor]

An alien retaliation mission has a small chance to be launched when an UFO is downed by XCom, or can be selected in the later months as that month's mission.

The first step of an alien retaliation mission is to send UFOs to look for a base in the region where the mission is launched. If you turn aggressive retaliation on, it makes every UFO pay attention to their radar, so any UFO that flies close to your base may find it. With the option off, UFOs that are not on a retaliation mission are just flying to their next waypoint and will not find a base.

I am not sure if a UFO on a different mission finding a base is enough to send a retaliation however.

In the same vein, would it be possible for destruction of a landed UFOs to also have a chance to launch a retaliation? It's a bit weird how the aliens don't care if you assault them when they landed on their own but will try to take you out if you make them crash before assaulting. The end result is exactly the same: they lost an UFO, so they should react similarly.

[SIMON BAILIE]

it's a divisor

short version is:

detectionOdds = detectionOdds / (1 + numberOfMindShields)

1 is good (50%), 2 is better (33%), 3 is excessive, but probably the sweet spot in terms of bang for your buck (25%), and you won't see nearly as much of a return on a 4th (20%).

What I was actually wanting to know is what are the detection odds as a percentage if possible, as Warboy has stated? I understand that if u had 2 mind shields this chance is only 33% of that but it's the original % chance I was wanting to know.

[7Saturn]

Base defenses installations are actually useless.

Maybe not in the beginning, but then you just have the less effective defences. But the effective ones (fusion, plasma) are accessible rather late in the game, when you don't necessarily need them any more. I only use them for bases, where bad trained soldiers are on duty.

It's better to get rid of the retaliationmission with a base defense mission, i usually skip them totally.

Especially annoying is the fact, that they will keep coming until they succeeded in landing at your base. (Which in turn means, having to defend your base in battle.) I used to play 4 fusion + 1 grav shield + 1 mind shield. Takes an awful lot of space and will bring you to the point, where you gladly raze your fusion defences, just to get rid of those constant attacks. In the lategame you will have quite a lot of tries, except, when you simply kick their butts after landing. Then they will need some time, until they find you again. So yes, mindshields are probably the best way to go.

[Meridian]

What I was actually wanting to know is what are the detection odds as a percentage if possible, as Warboy has stated? I understand that if u had 2 mind shields this chance is only 33% of that but it's the original % chance I was wanting to know.

It is not just a fixed number... it depends on the size of the base, aggresive retaliation option, on time spent searching for the base, on distance from your base and maybe more parameters. You don't really need (or want) to know how exactly it works.

If you insist... I had a quick look and my rough interpretation of the source code is 15-21% base chance depending on base size, divided by the number of mind shields+1. Then, if UFO is close enough to your base, it has this chance to detect your base once every 10 minutes. (I may be wrong though.)

[7Saturn]

Does this apply for human base-search as well? BTW: I very often found alien bases well outside of the radar-range. Is this kind of a bug, or on purpose?

[Meridian]

It doesn't apply to human base-search... it is much easier for XCOM ;-)