No way in hell

[7Saturn]

I have no idea how something like this would be calculated.

And the important part: How would you show that to the player? Right now, accuracy is just shown, when you click on the weapon and choose the type of attack/usage. At this point, the engine simply doesn't know, where you will end up pointing it to. So you'd have to choose the target first, then the engine assesses the accuracy at this target, and then you'd have to have a chance to reconsider your choice. I don't think, that this would improve gameplay for all those situations, where obstacles aren't a big problem. And if the engine could assess the very high likelihood of failure on that specific target (let's say, .1% chance), it could as well simply refuse to point there, as it does with targets, that have in fact 0% chance of hitting.

[Bloax]

There's no need to calculate it, it's already done for you through the fact that the larger the target is, the easier it is to hit them due to taking up more space for projectiles to hit.

[Shoes]

And the important part: How would you show that to the player? Right now, accuracy is just shown, when you click on the weapon and choose the type of attack/usage. At this point, the engine simply doesn't know, where you will end up pointing it to. So you'd have to choose the target first, then the engine assesses the accuracy at this target, and then you'd have to have a chance to reconsider your choice. I don't think, that this would improve gameplay for all those situations, where obstacles aren't a big problem. And if the engine could assess the very high likelihood of failure on that specific target (let's say, .1% chance), it could as well simply refuse to point there, as it does with targets, that have in fact 0% chance of hitting.

Ineresting question. What if you were trying to hit a tree? The engine would have to somehow know what you are aiming for and use it's projected surface area in the multiplier calculation. It doesn't fix the problem, only "fixes" the alien part of the problem.

[Nikita_Sadkov]

"The algorithms were, of course, very fun to construct and interesting to discuss outside of the game. The players, however, felt left behind -- the computer was having all the fun -- so we cut the feature. Further, games require not just meaningful choices but also meaningful communication to feel right. Giving players decisions that have consequence but which they cannot understand is no fun. Choice is only interesting when it is both impactful and informed." --Sid Meiers, on Civilization game design

[Solarius Scorch]

"The algorithms were, of course, very fun to construct and interesting to discuss outside of the game. The players, however, felt left behind -- the computer was having all the fun -- so we cut the feature. Further, games require not just meaningful choices but also meaningful communication to feel right. Giving players decisions that have consequence but which they cannot understand is no fun. Choice is only interesting when it is both impactful and informed." --Sid Meiers, on Civilization game design

Pity the Master of Orion ]|[ lead designer didn't think like this. And Distant Worlds people too.

[yrizoud]

It's a decent point. In vanilla UFO / X-COM, alien events seemed totally unpredictable to me. It's only since following OpenXcom that I learnt there was a system of monthly, race-specific "missions", and that killing scout crafts would cancel the rest of it.

[kkmic]

That would mean that a soldier with 100% firing accuracy will have a 100% chance of hitting an exposed alien (100% of it is visible) and 25% chance of hitting an alien that is 75% hidden by cover, which is pretty natural IMHO.

However this creates the issue that OXC might show 100% or more accuracy for a soldier, but since the actual chance of hitting the alien might be 10% or less, the game will let you fire and you will have no idea why nine out of ten shots go wide...

This must go hand-in-hand with an accuracy display on cursor.

[7Saturn]

However this creates the issue that OXC might show 100% or more accuracy for a soldier, but since the actual chance of hitting the alien might be 10% or less, the game will let you fire and you will have no idea why nine out of ten shots go wide...

Which get's even worse, when the actual probability to hit the target is far less than 10%, more like 0.1% to 0.01% or something like that. That's what's annoying people right now but it's not that sharp defined. So it also applies to your scenario.

[Dioxine]

This must go hand-in-hand with an accuracy display on cursor.

No it doesn't. The game shouldn't just let you fire impossible shots. It should be up to player to decide if he should try firing anyway, regardless of cover. Unless we throw the whole bullet tracing out of the window.

Basically the best idea IMO was hammered out on Volutar's thread: he wanted to write a tracing with 100% perfect accuracy (if the game says you have 100%, you will hit 100%, even if you see just a single enemy pixel); if a random spread was added to that (say, in normal conditions, it'd be like 8x8 pixels representing a normal-sized target), the result would be "100% means 100% chance to hit a standard-sized, unobstructed target" which would be both realistic and basically non-computable for the purpose of cursor-display (basically it'd have either to account for every tile along the way, or show a false number). That spread could be lowered for >100% accuracies, say by 1 pixel per every 10% above 100, or ruleset tweaks. Naturally if only a few pixels were visible, for example just enemy's head, the standard spread could well mean shooting above enemy's head or hitting cover. The player wouldn't be surprised as he would clearly see that those 9 missing shots were very close to the target, and each went by a slightly different trajectory (in current system, all 100% acc missed shots always follow the same, erroneous path which is simply frustrating and shows that you miss due to a glitch). To make this even more sensible the engine would try to aim at a pixel which is both visible and closest to enemy's centre of mass. One of the biggest advantages of such a system would be realistically working cover - instead of exploiting aiming glitches, players would choose cover naturally, and kneeling behind a boulder would actually increase your chances of survival by a non-negligible degree.
However, with Volutar gone, chances of such an engine emerging are slim... Also the spread would have to be optional since there was no spread in vanilla - one-pixel shots routinely connected if accuracy was 100% or more.

Getting back to my initial denial, I'll explain it more now: as a player, I'd rather have the cursor displaying an 'ideal' number and leave guessing my real chances to my experience (as long as the engine is flawless), than have it displaying some machine-calculated probability that is rather confusing than helpful. Manual control. I don't need the cursor to tell me that there is cover in the way, as I can see it for myself. Also, when I force-fire through full cover, the cursor showing '0%' would be plainly and completely misleading.

[Yankes]

I would prefer system when you could miss "aiming". Something like separation of weapon accuracy and human accuracy.
a) try find perfect trajectory, you have couple trials based on only on solder accuracy to find random trajectory that can hit enemy.
b) do normal shoot using found trajectory.
This will prevent wasting all your ammo on small obstacle that was on the way but will prevent you hitting enemy in foot form end of map.

[DeltaEpsilon]

For accuracy: I suggest adding as option a mode, which makes game show maximum deviation in degrees instead of vague "accuracy". Because not only is it maybe more convenient in certain situations, but also because new players are prone to think of "accuracy" as change of hitting. Heck, even I was like that some time until I got myself to UFOPaedia.

[Dioxine]

I don't know, the max deviation is fun info for science but I don't particularly care by how much will I miss if I don't hit (there's a simple function for that - or actually 3 linear functions chosen by a conditional statement, as far as I can tell, it goes to about 0 for about 160% acc, and you will still miss if the trajectory is affected by the glitch the OP brought up). I'm more interested in practical issues, ie. how likely I am to hit. The accuracy, understood as 'accuracy under lab conditions', is far more informative IMO.
But maybe it's just me - to me personally is rather obvious to not fully trust any kind of simplistic evaluations to complex problems, especially if the evaluation is done by a machine. Useful, sure, but still just a guideline.
And the 'lab accuracy' is very useful - if 'true acc calc' would be somehow implemented, it would deny me the knowledge of how likely I'll be to hit if the current obstructions were gone... It will, like a genius moron, tell me that I have 0% chance of hitting an enemy who's behind a wall...

[The Reaver of Darkness]

Is this the same bug as the one in which sometimes you hit an alien way too many times and it won't die? I suspect this one is a bit different. It seems that you're apparently not actually hitting them, but the graphic appears to have shown you hitting them. It happens with aliens in certain spaces, like the passable alien craft rear wall segments, which weren't passable in the original game.

[Solarius Scorch]

Is this the same bug as the one in which sometimes you hit an alien way too many times and it won't die? I suspect this one is a bit different. It seems that you're apparently not actually hitting them, but the graphic appears to have shown you hitting them. It happens with aliens in certain spaces, like the passable alien craft rear wall segments, which weren't passable in the original game.

I don't think I've heard about this, but indeed it cound be true. The problem is, without proper debugging tools it's impossible to determine if the fact that Sectoid didn't die after being hit three times from a laser rifle is a bug or he was simply very lucky - after all it could be three bad rolls on your part. But yes, it's possible it's some sort of a bug, and it could be related to the obstacle bug.

[yrizoud]

Causing no damage is not a bug, it's a probability. 4 hits in a row which don't cause visible damage is not a proof of anything. If you have doubts, put some logging code, which prints out the damage rolls (min, max, randomly picked). When If you experience  a suspicious series of events, look at the logs.