Anti Alien Infiltration (using save scum and beginner difficulty)

[Escape123]

is it possible to completely defend against all infiltration missions if i shoot down the scouts in "phase 1" as according to the official game guide? assuming you can save scum to prepare in advance

also what determines phase 1 infiltration scout mission success? do you need to shoot the scout down over water before the time it touches land of that country? can you ground assault a landed phase 1 scout and also have that successfully stop infiltration?

[Colonel Sanders Lite]

Edit -
Starving Poet says it better and more accurately than I do.

[Starving Poet]

Is it possible to prevent an infiltration?

No. Not at all. The only RNG is when the infiltration mission spawns in a region. Once they start, they can't be stopped. They also take down the countries in a region is a specific order.

If you want a breakdown here's how they work.

1. There is a small chance every month that an infiltration mission will spawn. It has nothing to do with score, funding, or whatever. It's pure RNG.

2. When that mission spawns it will choose a region - NA / SA / Europe / etc. Because you can't have two of the same mission type coexisting in a single region, you can't have two infiltrations happening in NA at a time. The order that the countries in each region get infilitrated is hardcoded. Nothing you do can change it, score, activity, etc are irrelevant.

3. The first scout wave will spawn. If you shoot it down the game will roll up to one extra week before spawning the second wave. If you let them linger, then it will spawn the second wave immediately.

4. Repeat Step 3 until the Battleship wave approaches.

5. AS SOON AS THE Battleship wave spawns, the mission is considered a success, the aliens build a colony in the first free country in the list, that country leaves the council.

6. As soon as the mission completes - spawn a new mission to start the 1st of the next month in the same reason indefinitely.

tldr; Nothing you can do will stop infiltrations once they spawn. You can delay them a month or so from completing, but you can't stop them once they start.

[Tetsuri]

we must not be playing the same game. When I shoot down scouts, that's the end for those infiltrations.

[Starving Poet]

The code has all been decompiled over the years. Unfortunately in terms of inner engine workings, there's no mystery left to UFO or TFTD.

[Tetsuri]

I think we both know that if you shoot down the scout, the infiltration is deterred. So Idk why you added all those extra words to mislead. It's true that you can't PREVENT any mission from INITIATING, but if you're trying to imply that you can't stop the infiltration, then that is false.

[Starving Poet]

No, it's not. The infiltration mission consists of the following waves:

    waves:
      - ufo: STR_SMALL_SCOUT
        count: 1
        trajectory: P0
        timer: 16500
      - ufo: STR_MEDIUM_SCOUT
        count: 1
        trajectory: P1
        timer: 15000
      - ufo: STR_MEDIUM_SCOUT
        count: 1
        trajectory: P6
        timer: 13800
      - ufo: STR_LARGE_SCOUT
        count: 1
        trajectory: P7
        timer: 9000
      - ufo: STR_LARGE_SCOUT
        count: 1
        trajectory: P7
        timer: 60
      - ufo: STR_TERROR_SHIP
        count: 1
        trajectory: P7
        timer: 60
      - ufo: STR_SUPPLY_SHIP
        count: 1
        trajectory: P7
        timer: 60
      - ufo: STR_BATTLESHIP
        count: 2
        trajectory: P7
        timer: 60

The timer field is how long after the previous wave should this wave spawn in minutes. Like most things in xcom, this number can vary by 50-150%.

If you shoot down a wave, the next wave will have an additional delay of (30 * (RNG::generate(0, 400) + 48)) minutes or between 1 and 9 days.

This means that in an ideal situation, shooting down the first scout wave can extend the arrival of the medium wave by (15,000 * 1.5) + 13,440 minutes. That winds up being 25 days and will almost always push you past the end of the month giving the "implication" that the mission ended, but it didn't. This mission, however, can just take multiple months to complete.

You can't stop missions in xcom from completing before they hit the final wave. There is no logic for it.

[Tetsuri]

infiltration is just like retaliation. If you shoot down the scout before it accomplishes the objective, the second stage is never launched. It seems like you pulled only stage 2 data and just omitted that there is a stage 1 to this mission.

[Colonel Sanders Lite]

You are wrong tetsuri. All the data is right there. The first four waves in that list are the first stage you're talking about and the rest are all the second stage you're talking about.

That is straight from alienMissions.rul if you want to check it for yourself.

I didn't spot any innacuracies in Starving Poet's posts. This *is* definitively how it works in open x com.

The only real point at which any of this can be disputed is arguing with the guys that reverse engineered the vanilla game. TBH though, I'm pretty confident that they got it right.


Edit -
Also, to stop a retaliation, you have to shoot down or hide from *8* UFOs. If any one of them finds your base, the assault battleship appears. Once the assault battleship appears, it will keep appearing until it successfully lands on your base.

[Tetsuri]

okay, I know what you're saying, but I've never experienced that. It's always just small scouts sent on my infiltrations, and they even send them again, but it doesn't progress beyond that for me.

[Colonel Sanders Lite]

You're not playing openxcom *extended* are you? There is an option in there to interrupt missions but it's not vanilla.

I have had aliens keep sending more retaliation scouts and even the battleship scouts plenty of times.

[Tetsuri]

sorry, I edited the message, I meant infiltration and not retaliation. It's possible I just haven't been in any particular game long enough to get up to these final infiltration steps, but I don't know, I always take my time to max troops, and after I got full coverage, I never had any bigger ships sent on infiltration.