Throwing Accuracy is one of the simplest skills in the game and only performs one task. It controls how well a soldier is able to actually hit the target tile with a thrown object. Nothing much else.
Throwing Accuracy works in conjunction with Strength, where one controls the accuracy of the throw, the other controls the range of the throw depending on the weight of the object.
New recruits will always begin with a value between 50 and 80.
Throwing Accuracy points are awarded (at end of combat) depending on how many times you throw objects. (How obtuse is that?) If your throw misses its intended target/square, it still counts as a throw.
You are awarded an average of 2 skill points (range 1-3) per combat mission if you make at least 3 throws, and an average of 4 (range 2-6) for 11 or more. The point award does not depend on your current skill level, only on the number of throws. For more particulars on skill-point increases, see Experience. Note that unlike any other primary skill, throwing does not trigger an increase in secondary skills (TUs, Health, Strength, Energy). That would've been too easy!
All in all, few people bother much with this skill. But if you're interested in it, note that the maximum gain for minimum personal (real world) time spent, would be to have your soldiers throw 3 things each mission. Probably just before ending a mission.
An X-COM soldier's Throwing Accuracy is capped at 120. However, because you can get a +6 roll when at 119, a soldier can have up to 125 Throwing Accuracy (if they're really lucky — and dedicated as hell to chucking stuff!!). For more info, see Regarding Caps.
Throwing Accuracy is also affected by critical wounds and health percentage:
Throwing Accuracy = Base Throwing Accuracy × a × b
- a = 1 - 0.1 * Wounds(capped at 9)
- b = current health / max health
While not exactly Throwing Accuracy, this is as a good a place as any for this:
Throwing Distance roughly = 2.5 × Strength / Weight
The "2.5" appears to vary from ~ 2.1 to 3.3. The "2.5" is an approximation for Strength_Multiplier/Maximum_Throw_Range. To find the exact value you can use the .XLS file linked below.
When weapons are tossed, the weight of the ammo (if loaded) is not counted. (But weight from loaded ammo does otherwise count for weighing down a soldier carrying the weapon.)
As NKF points out, the throw always travels in an arc. Sometimes this arc is blocked by Skyranger wings, overhanging trees, ceilings, or even the 4-level-high virtual ceiling of the Battlescape itself. This results in the message "Unable to throw here!" even when the line of sight is clear.
Kneeling allows you to throw farther under ceilings, increasing this distance slightly.
Throw Range forms a box, not a circle. If your soldier can throw an object 16 tiles straight ahead, he can also throw 16 tiles diagonally. The Following is an .xls file which shows how maximum throw ranges are calculated, and can calculate how far a soldier with a given strength can throw any item:
There are only 21 maximum throw ranges: 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 16, 18, (22)21, (27)23, (35)27, (51)33, (??)46, -1 (unable to throw) - you will only see the last 2 if you hack .DAT files. For (X)Y the X represents the maximum range before you receive the "Out of Range!" message, and the Y represent the maximum range you can throw (beyond that you receive the 'Unable to throw here' message due to the limited height of the battlespace).
Note: the following only applies if you hack X-Com data/savegame files
Maximum throw range is a signed integer, so if you hack your soldier's strength too high or an item's weight too low it will become negative rendering your soldier unable to throw lightweight items. Throwing with 0 strength crashes the game.
|X-Com: Enemy Unknown/UFO Defense|
|Soldiers:||Time Units • Energy (Stamina) • Health • Bravery • Reactions • Firing Accuracy • Throwing Accuracy|
|Strength • Psionic Strength • Psionic Skill • Melee Accuracy • Stun • Morale • Rank • Fatal Wounds|