Talk:UFO Exit Ambush

Do aliens get the first shot in "mutual surprise" situations when it's their movement turn? I only tested it for X-COM troops. In not-formal testing, I've gotten the sense that it doesn't apply to them... or maybe it's just that they don't always make use of it and move (instead of shooting) after entering visual range. I guess some testing is in order... if I can get the aliens to cooperate.--Ethereal Cereal 21:34, 16 March 2007 (PDT)

I tested this shortly after the "mutual surprise" rules went up. The rules are exactly symmetric (I have had Floaters get a free shot on camping 60+ Reaction soldiers). However, there are two conflating factors:

• The actual visibility calculations are wonky. E.g., it's possible for a crouched soldier to see a floater over a low brick wall, during the alien turn, but not during one's own turn. Also, there are differences between line-of-fire and line-of-sight calculations; turn-swapping suggests that it is possible to reaction-fire on targets that are not visible because of fences.
• In some circumstances, the aliens may get confused and oscillate between cover and attacking.

--Zaimoni 1:40, 17 March 2007 (CDT)

Interesting. This would mean you want to avoid the 90 degree area immediately visible to an alien walking through the door. It's funny how I tested mutual surprise so extensively for X-COM troops but never thought to test it for the alien side. I've got some work to do. ;-)--Ethereal Cereal 02:14, 17 March 2007 (PDT)

Well, based on my testing, "mutual surprise" does not hold true for aliens on their movement turn. I had a high-reactions soldier stand in front of a door. An alien stepped out and got shot down. If an X-COM soldier went through a door and spotted an alien in front of him, he could get off one shot (or other action) before the alien would react, no matter what the disparity in reactions/TUs.--Ethereal Cereal 01:02, 21 March 2007 (PDT)

Direct contradiction of what I've seen, so we need to track down what's going on. I only have CE Edition currently; XCOMUtil should not make a difference since that would be a disassembly hack (disallowed by employment contract). I'm currently playing with unmodified craft, though. Current testing for UFO Flight Patterns is with no alterations in Battlescape.

The following setups have gotten free shots for Soldier Floaters on my system when "no mutual surprise" would have given a reaction shot. X is an XCOM unit, x is the XCOM unit that takes the free shot:

"Just too close"

-- --
  f


 x

[x has 53 Current Reaction, does not get reaction shot]

"basic scattered firing arc" (horizontal X is 20 squares away, so one less XCOM unit is the maximum one-sided scattered firing arc that doesn't risk mutual surprise. Horizontal X should have high accuracy to prevent friendly fire, not required for others. Horizontal X is camping with 60+ reaction, but does not get reaction shot)

                  -- --
X                   f
  X
   X
     X
      X
        X
         X
           X
            x

We need to think of other variables to check, evidently. The "turns since XCOM unit was last spotted" would be a good one to look at, I didn't know where that was when I did these tests. I'm not so sure about targetability of the square the alien moved from after the door opens.

--Zaimoni 10:31, 21 March 2007 (CDT)

One other but highly unlikely explanation would be that the alien spotted the X-Com unit just before moving through the door thanks to some wacky line of sight calculation. Again, that's highly unlikely.

Also, X-Comutil shouldn't affect the game while it's playing, only when it's switching between the geoscape and battlescape, so that wouldn't change the opportunity fire mechanics. - NKF

There are certain factors (like alien "Intelligence" and funky LOS situations) that probably complicate testing. However, here's my save game, which doesn't seem to have those as factors: Media:Rf testing.zip. "Dave" stands outside the UFO door and waits about 10 turns before the aliens come out. All other X-COM units are hidden. All units are hacked to 160 current/max reactions to eliminate the chance that they're simply losing a Reactions battle. When the aliens come out, Dave shoots them. If mutual surprise were in effect, the aliens would get the first shot. --Ethereal Cereal 18:05, 21 March 2007 (PDT)

Fun. Of course, 160 reactions never occurs in a real game post-1.0 (the highest possible with stat cap is 81). Perhaps mutual surprise simply imposes a large penalty to Current Reactions? --Zaimoni 18:01, 22 March 2007 (CDT)

Also, I've downloaded that test game: it's suitable for tweaking into a binary search. I should get some in vivo tests going with my next floater mission (while may be a while, work schedule went haywire again). --Zaimoni 18:18, 22 March 2007 (CDT)

I believe the highest Reactions possible is 105 (99+6). That's enough to beat Superhuman Ethereals (93 Reactions). In my testing with X-COM's side, a soldier can have terrible reactions and almost no TUs remaining, but the alien will still not shoot at a soldier as long as they both just spotted each other. So it's not a case of a penalty, it's a special case which gives X-COM scouts a fighting chance. There are a number of cases where blind spots seem to screw up the rule, but those boil down to getting spotted first.--Ethereal Cereal 18:18, 22 March 2007 (PDT)