How does cover work?
From what I can tell, your units either have no cover, partial cover, or full cover relative to an enemy unit. However, even "full cover" doesn't mean "can't be shot", as I've definitely lost soldiers to plasma rifle fire in the face when they were behind full cover.
How does cover work? What kind of defense bonuses do I get for partial or full cover? I'm looking for numbers here if possible.
Cover only affects hit chances. (The single most important thing to consider on impossible) Objects in the game affect Line of Sight.
Aim is the base hit chance. 65 Aim = 65% hit chance. SCOPE increases, sectoid mind link, overwatch decreases it,...
Cover adds to your defence stat. Defence reduces the enemy hit chance. 20 Def = -20% hit chance. Remember that cover only reduces it aslong as the unit takeing the shot did not flank you.
Range then has a final effect on hit chance this can be positive or negative depending on the weapon. Shotguns positive hit close negative long range, snipers neutral long negative short.
Hunker down doubles the cover bonus! (cover not defence eg smoke grenade or ghost armor) While I read many people consider cover broken inaccurate etc. I find that the game treats this very very precise except people consider aliens aim as crappy as your soldiers. They dont especially mind linked and on impossible they hit hard.
Hunker down as such should not be overlooked. Defence and LoS is the only way to avoid damage health just lets you soak up more before you die. Big hint for all that try impossible and find they fail.
Now the numbers you asked for:
- Partial cover +20 defence (Cover type)
- Full cover +40 defence (Cover type)
- Hunker down doubles cover type defence
- Being flanked removes cover type defence
- Smoke grenade adds +20 defence or 40 if skilled. (Normal defence)
- Various armor adds defence (ghost +30 Normal defence)
- Normal defence apply's even when flanked
I have not bothered with counting exact squares for optimal ranges yet. There is a very very limited weapon base in this game and you will get a feeling of all of them soon enough. Getting shot? Hunker down stop shooting those crappy low hit overwatch shots at dashing aliens Disagree? Talk when you never lost a man on impossible