Is there something like a critical fail or something? Several times I took a 150 something % to shoot someone and the shot hits obstacle... ok, I can bite that.
But having 218% to hit with sniper and missing by 2 squares is kinda hard to swallow. Is there some other factors to be counted after I click to shoot when it shows such % to hit?
There is only one thing that's wrong... and that is the percentage symbol.
What you see displayed as 150% or 218% is
NOT a "chance to hit", it is your effective accuracy and should be displayed as a plain number, e.g. just 150 or 218.
The original game showed it with the % symbol and that is the only reason why OpenXcom also displays it like that... but it's a pure lie.
The game doesn't work with "chance to hit" at all, so please forget about that concept completely.
What the effective accuracy means is also not easy to explain, so I will just give you 3 examples with some background.
Example 1:
- you and your target are both on the same Z-level
- there is a line of fire between you and your target... and it is not obstructed by any objects (trees, bushes, fences, lamp posts, etc.) within 0.5 tiles from ideal trajectory (LoF) in all directions (up, down, left, right)
- in such conditions, effective accuracy of 110 is enough to have 100% chance to hit a reasonably big target (e.g. an alien) across the whole map
Example 2:
- some conditions from example 1 are not met, e.g. you are on different Z-levels... or there is LoF, but there are some obstacles very near to this ideal LoF (nearer than half a tile)
- in such conditions, even accuracy 110 is not a guarantee to hit... higher accuracy will help (i.e. 218 is better than 110), but increase comes with very diminishing results... in such scenarios you are likely to hit maybe 50% of your shots
Example 3:
- there is a LoF, but there are many obstacles very near to this ideal line
- in such a scenario, your chance to hit is very low (~5%) regardless of the effective accuracy, even if it is 250+
And as always, there are even more factors I haven't mentioned, like:
- how much of the target unit do you actually see (ideally you should always see the whole target, i.e. no partial cover)
- there is small discrepancy between checking LoF (from eye-level) and shooting (from shoulder-level)
- etc.
From all this, you should remember:
- the number you see is NOT a "chance to hit"
- 110 is very good, anything above will not give you much more benefits
- if the shot looks complicated (many obstacles around the ideal line; or target in partial cover)... you will most likely miss... don't push it and find a better place to shoot from
It's not part of the mechanics, it's an imperfection of the engine. It is a well known bug, at least among devs and such, but it's so complex to fix that we just have to live with it - at least for now.
From my perspective it's not a bug.
There are some very small things, which could be improved/fixed... but in general, it works as designed.
Again, the number you see does not represent a chance to hit... it's a much more technical and mysterious number, which should be taken as an indicator, not as a fact.