Thrown explosive

A thrown explosive is a type of weapon that has existed in some shape or form in every Fallout game.

Fallout, Fallout 2, Fallout Tactics
In Fallout, Fallout 2, and Fallout Tactics thrown explosives are governed by the Throwing skill. Like other thrown weapons, thrown explosives are based on Strength to determine range, but because grenades in these earlier games have a maximum range of 15, a Strength more than 5 is redundant (range is 3 tiles x Strength). Unlike other thrown weapons, thrown explosives detonate upon hitting their target, dealing damage to both the target tile as well as all adjacent tiles (though some explosives in Fallout Tactics have wider areas of effect). Moreover, thrown explosives cannot be targeted, which makes combining Fast Shot with judicious use of grenades a benefit without a downside.

Like missile launchers or other thrown weapons, thrown explosives, even if they miss, will still land in a hex tile roughly near the original target. However, unlike, say, a throwing spear, instead of landing on the ground, the explosive will detonate. This can mean that a miss can still hit the original target. It can also mean that a critical miss, in which the player drops their weapon, can be particularly bad. It also makes urban combat more problematic, as a miss can easily hit an innocent bystander, thus rendering the entire city hostile.

In general, thrown explosives are rare and expensive. In Fallout 2 however, random encounters that feature Hubologists will have plasma grenades that can be stolen.

Named perks

 * Heave Ho! will increase the range of thrown explosives for characters with Strength less than 5 and who never plan on wearing Power armor.
 * Demolition Expert, despite its description and implementation in later games, does not affect thrown explosives.

Fallout and Fallout 2 thrown explosives
Fallout thrown explosives, 2

Fallout Tactics thrown explosives
Fallout Tactics thrown explosives, 2

Fallout 3, Fallout: New Vegas
In Fallout 3 and Fallout: New Vegas, thrown explosives are moved into their own skill category, Explosives, which also includes the dynamite and plastic explosives that used to be in Traps (Fallout: New Vegas only).

In Fallout: New Vegas, the Explosives skill in general is broadened to also include "explosive"-style guns, but extra traits and perks are included that help differentiate thrown explosives from other explosive weapons.

Sneaking
Unlike in previous Fallouts, thrown explosives can also be used like placed explosives when it comes to planting them on a target. Reverse-pickpocketing any thrown explosive onto a target will change the explosive into a "Live" version of the explosive, which will then cause a fatal explosion a few seconds after the player closes the stealing interface.

Note that this explosion is always fatal, regardless of whether a flimsy Dynamite is used or a devastating Nuka-grenade.

Thrown explosives can also be used to land sneak attacks, though is a bit more difficult than other weapons for two, unfortunately contradictory, reasons:
 * The projectile may directly hit the target. Sometimes, but not always, the impact (and subsequent minor damage) is enough to put the player into [Caution].
 * The projectile may hit other obstacles near the target. Sometimes, but not always, this may be enough to alert the target to negate sneaking.

Real-time combat
All thrown explosives in real-time combat have a fuse: they do not detonate based on proximity or on contact. This means that significantly leading the target becomes a necessity, though the wide area of effect of most thrown explosives alleviates the need for precision aiming. Moreover, unlike having placed weapons, a high Explosives skill does not increase the amount of time the player has to avoid an enemy thrown explosive.

Thrown explosives can be shot to detonate them prematurely, however, the resulting explosion deals no damage.

Similar to melee combat, holding the attack button down alters the nature of the attack. For thrown weapons, it increases the throw distance, up to a maximum range. Because the fuse of a thrown explosive doesn't start until actually thrown, a thrown explosive can be primed for maximum range almost indefinitely.

In V.A.T.S.
Along with Melee Weapons and Unarmed, targeting individual limbs with thrown explosives is impossible. Though, enemies will still be likely to have body parts crippled from the sheer breadth of the explosion. Moreover, because thrown explosives have a finite range (again, much like close-ranged melee/unarmed weapons), a step or two in the wrong direction can change a moderately good chance of hitting to a 0%.

Even with a 95% chance to hit, this in large part means that - by the game's calculations - the explosive component of the weapon will have a 95% chance to hit. Moreover, this assumption is based on another assumption: that there is a surface for the explosive to land upon. This means that an enemy on a narrow ledge, for example, may be virtually impossible to hit despite a high projected chance: the game frequently assumes that the grenade will be able to land on an imaginary surface, when in practice it will sail past the enemy.

Moreover, when throwing an explosive in V.A.T.S., the projectile follows a parabolic arc. This has the side effect that shots with a high chance to hit may still miss in certain situations. For example, throwing a grenade at a far target when standing right behind a doorway will almost guarantee that the grenade itself will hit the top of the doorway and fall right in front of the player. This is not too much of a significant issue in Fallout 3 where players only take 10% normal damage in V.A.T.S., enemies are more aggressively slown down, and frag grenades virtually infinite. This becomes a more significant issue in Fallout: New Vegas when the player takes a much more significant fraction of normal damage (75%) and enemies are better able to close the distance in the time spent waiting for the botched grenade to explode.

Thrown explosives can also be individually targeted in V.A.T.S. Moreover, in Fallout: New Vegas, the likelihood that a player's thrown explosive is hit in mid-air by an enemy shot increases, mainly due to changes in V.A.T.S. mechanics and the greater proliferation of burst-fire weapons.

Fallout 3

 * Demolition Expert will increase the damage done with all explosives by 20% per rank (max 60% with three ranks).

Fallout: New Vegas

 * Loose Cannon makes throwing explosives much faster, in both real-time and V.A.T.S. mode, at the cost of significantly decreased range outside of V.A.T.S.
 * Heave Ho! increases the range of throwing explosives, in addition to increasing their real-time attack rate.
 * Demolition Expert operates identically as in Fallout 3.
 * Hit the Deck increases your DT against all explosives, which can be useful if a grenade falls short of its target or detonates in your hand.
 * Splash Damage increases the area of effect of all explosives.
 * Mad Bomber unlocks crafting recipes for many thrown explosives, including the most powerful in New Vegas.

Fallout 3 thrown explosives
Fallout 3 thrown explosives, 2

Fallout: New Vegas thrown explosives
Fallout: New Vegas thrown explosives, 2