Why do shots at 100% or above miss?

[GrooveCrusader]

I'm not entirely sure why nor can I really find a proper explanation as to why but its something thats been happening as far as I can recall when I started to use mods for OpenXcom for the first time. I always assumed it was due to objects in maps blocking the shot that got in the way, though I've also noticed this phenomenon on maps with little to no objects where this odd situation occurs on. For years I always assumed this was either a bug or a weird and amusing quirk of openxcom and never thought much on it till now after making a damage calculator in google sheets haha.

So why do shots at 100% or higher miss? 

[Meridian]

Simple answer: it is not 100%, it is just 100

Long answer: https://www.ufopaedia.org/index.php/Accuracy_formula#Use_of_Accuracy

[GrooveCrusader]

Simple answer: it is not 100%, it is just 100

Long answer: https://www.ufopaedia.org/index.php/Accuracy_formula#Use_of_Accuracy

Ah! I see, thank you very much 

[Majamas]

Does using a two-handed weapon in one hand have any penalty to accuracy in the game mechanics? when, for example, we have a rifle and one hand is occupied with something else, e.g. a motion scanner?

[Alpha Centauri Bear]

I recall some mods or mini-mods claiming to place "real accuracy" at the target. Is this a true real chance to hit or just another presentation of same accuracy stat?

[Meridian]

I recall some mods or mini-mods claiming to place "real accuracy" at the target. Is this a true real chance to hit or just another presentation of same accuracy stat?

Some mods or mini-mods may or may not do whatever they do or don't do.

How are we supposed to answer a question about an unknown mod?

Does using a two-handed weapon in one hand have any penalty to accuracy in the game mechanics? when, for example, we have a rifle and one hand is occupied with something else, e.g. a motion scanner?

yes