11 replies to this topic

[Trevelyan]

Ok, so how are reaction shots done based off of your Reaction stat?

say i have a person with 50 percent reactions... does that mean if he/she sees movement they will reaction fire 50 % of the time?

[slavafetisov]

I thought Reaction speed was a straight stat comparison... highest Reaction rating goes first.

So when a Sectoid with a 45 reaction (making that up) runs into a Squaddie with a 55 reaction, the Squaddie shoots first... but if a Squaddie with a 55 reaction runs into a Muton with a 60 reaction, then the Muton goes first.

[Robo Dojo 58]

Okay, these are personal observations, but I may be wrong.
I've noticed that making alot of smaller moves gives aliens a greater chance for opportunity shots.
I've also seen that distance may be a factor. Units further away seem to have a lower chance of doing opportunity fire.
I don't know the exact formula, but a reaction of 50 is extremely high, and a reaction of 20 is practically worthless.
These are just personal observations, so I may be wrong.

[slavafetisov]

Makes some sense that smaller moves trigger more "chances", I guess... however, if I'm in the middle of a longer move, I think the aliens shoot at the first opportunity (if they have TUs left) and freeze my squaddies in their tracks, thus triggering "smaller moves".

Reaction fire seems to take place per action... so if something expends TUs in LOS of a unit that is capable of Reaction fire (has TUs remaining), then Rxn fire will occur. Even turning can trigger it... I think it's just a matter of expending a TU in front of something that has TUs left.

Example: Squaddie moves into LOS of Sectoid with Plasma Rifle... if Sectoid has higher Rxn stat, then Sectoid shoots immediately in the instant that LOS is achieved. If Squaddie has higher Rxn stat, Sectoid does nothing in that instant, and Squaddie gets first decision of how to expend TUs at instant of contact... but after Squaddie expends TUs, Sectoid has first opportunity to expend TUs (Rxn fire) afterwards. I think higher Rxn differences (Squaddie with Rxn of 60 vs. Sectoid with Rxn of 30) might give your Squaddie more TUs to expend before the Sectoid reacts... but I don't know for sure without a game to test right now.

Does distance matter? I'm not sure. In high visibility situations, if I am guarding the outside door of a UFO, I often put Squaddies at long range (you know the drill... surround the door of a UFO and wait for the Sectoids to hop out, exposing itself to massive reaction fire). I don't think the longer-range Squaddies have much/any reaction penalty for being further out... but I don't know.

(One reason why I love the Farm terrain: 2nd, 3rd, and 4th floor sniper posts for guarding the outside of a UFO, even at long range.)

I think that # of TUs left also could be a factor in reaction fire calculations (your reaction being calculated earlier in your turn), or at least it "should be" a factor in the calculation.

Anyone with a clearer memory of how it works probably has a better description of Reaction fire than mine.

[Trevelyan]

you must have some good soldiers to be able to do that to sectoids... when i tried that on them... their MC tore my whole squad apart.

[Cpl. Facehugger]

Unless there isn't a leader aboard that ship.
Like a medium scout for instance.

[slavafetisov]

Definitely if there is MC, it's a full-on rush to bag the leader. No way you can hang out and wait for MC to happen (especially during those times when you have no idea about the Psi strength of your troops).

Blaster bombs through the roof are nice if you know the layout and have a supply of bombs available... I've stormed a few bigger ships in my time to know how to park a blaster bomb in the control room of an alien Supply Ship, for instance.

There's always a few scout ships, though. And if you don't go under MC/Psi attack, why rush the interior of a UFO? It's just safer to lob a PD grenade, set up a firing squad, and wait for the fun to happen. I think reaction fire helps to train up the Reaction stat anyway.

It took a while for me to figure it out, but once I knew that I basically never had to go inside a UFO if there are no Psi attacks, then I figured out ways to put as many guns on the door of a UFO as possible... upper story windows, rooftops, laser/plasma-created holes in the exterior walls of upper floor buildings. Farm houses are perfect for this... crappy wood walls go bye bye even with peashooters (assuming you didn't clear a hole with a laser, then sent a Large Rocket inside the hole to flush out the bad guys).

[NKF]

It has been a while since this topic was started, but I think I can offer some insight on how reaction works.

Yep, they are a direct comparison between reaction scores. But there's a twist. The reaction score is the base reaction score, not the current reaction score. The current reaction score is hidden and you'd have to do a bit of mulitplication to work it out.

See, the reaction score is also adjusted by the remaining percentage of your TUs. Say you have a reaction of 50, but you have only 50% of your TUs left (say 30 out of 60 TUs). Your reaction of 50 is now whittled down to 25. ( 50 * 30/60 = 25)

So, general rule of thumb, the more TUs you have left over, the higher your reaction score. So as long as you have the higher reaction you get to shoot (on the alien's turn) or move without getting shot at if it's your turn (until your reaction runs low enough). Fast weapons, like pistols and laser pistols, are great for reaction fire mainly because they don't spend as many TUs as the plasma weapons.

So, even if the alien has a a daunting 70 reactions, if this alien has moved 50% of its TUs before it spots your soldier, all it'll really have is a reaction of 35, and your soldier who didn't move at all but only has 40 reactions will get off the first shot. Then it's just an exchange of shots by comparing the reaction levels of the two units, with the unit with the higher reaction getting off a shot. This repeats until both sides can no longer fire back.

Visibility is key, as a unit can only shoot at what it can see. If it can't see you, even if it has a reaction level of 255, it won't be able to shoot back at you.

There's yet another twist in this. On occasion either you or the alien may be able to spot each other without invoking a reaction shot if one side fails the reaction check. But this will only work once, and the moment another move is made (And assuming you can see each other), the bullets will start flying.

- NKF

General note: X-Com units can only use snap shots with reaction shots. The aliens know how to use auto and snapshots.

[Tsereve]

All hail the Algorithm Connoiseur, the Pistol Guru, that Master of all Things X-Com, NKF!

[Blehm 98]

NKF, what about aliens spinning to meet you and then killing you if you have already shot them, because i'm pretty sure that's happened to me

[Tsereve]

I suppose they notice you (and wouldn't you notice getting shot at?). Then, after you shoot, you have less turns, so their current reaction score is then higher.

[NKF]

Exactly. They are indeed alerted to your presence. And since you have to be able to see the alien in order to use opportunity fire against it, it will definitely be able to see you once it is alerted to your presence by the misfired shot.

So, your reaction score may be higher before the shot, but after the shot, your reaction will definitely be much lower. Of course, if you somehow manage to have the higher reaction score, you'll keep shooting until your reaction score is lower, and then the alien spins around and shoots you.

Just an example, you have 100% of your TUs and 52 reactions. The alien has 65% and 75 reactions. After the TU adjustement, you'd have 52 reactions and the alien will have 48. You've got a laser rifle and the alien's got a heavy plasma. On the next round, your 100% TUs will have dropped to 75% (laser rifle snaps cost 25% of your TUs, see?), so this'll leave you with 39. 39 -v- 48 and the alien gets the shot (heavy plasma snaps use 30%). Let's see it play by play:

Exchange 1
Soldier 100% * 52 = 52
Alien 65% * 75 = 48
Soldier fires

Exchange 2
Soldier 75% * 52 = 39
Alien 65% * 75 = 48
Alien fires

Exchange 3
Soldier 75% * 52 = 39
Alien 35% * 75 = 26
Soldier fires

Exchange 4
Soldier 50% * 52 = 26
Alien 35% * 75 = 26
(This one's interesting, I don't really know what the game does to break a tie - only that the alien actually gets 26.25 rather than a rounded figure of 26, so my guess is that the alien will take the shot - let's go with that one)
Alien shoots

Exchange 5
Soldier 50% * 52 = 26
Alien 5% * 75 = 3
(As the alien no longer has the TUs to shoot anymore, the soldier gets to fire the last two remaining shots unhindered)

- NKF

edit: Just so everyone knows how I figured this out, I used a psi amp and captured myself an alien (I think it was a floater, or possibly a muton). I armed it with a slow weak weapon and then planted it near a soldier in power armour with a weapon much faster than the weapon I gave the alien (namely, a pistol). Saved the game to allow repeating the test.

Then I got out a bit of paper, a pencil and calculator. Took the alien's max TUs (it would always start from 100%) and reactions and then took a note of my soldier's stats. Then I manually worked everything out on paper to work out the opportunity fire exchange sequence. This was simply a straight comparison of reactions after being adjusted by the health percentage after each shot is made.

Ended up something like alien, me, me, me, alien, me, alien, me (this sequence is just made up randomly). Then I actually tested it in the game and it went exactly the way I'd predicted. So I reloaded, and this time the same thing happened again. Did it a couple more times and it was exactly the same.

So I changed the soldier's overall TU percentage by walking or turning a bit, then recalculated the exchanges and came up with a new sequence. Not surprisingly, the alien and my soldier took their turns as predicted.

I really cannot remember what gave me the idea that reactions are influenced by a percentage of your remaining TUs. I always knew that the more TUs you had, the better you could react, even with a low score. Maybe by then I was catching on to the fact that the programmers really liked to use percentages in this game. Oh well.

Edited by NKF, 17 January 2005 - 06:06 AM.