This article is a stub. You can help out by expanding it. The editor who added this notice elaborates:This is generally very short for how many different mechanics projectiles have, and doesn't cover things like how they interact with line of sight blockers, how they can't rehit Bloons normally, how projectile count and spread works, etc
A projectile is a type of object created by an action from another entity in the Bloons TD series, Bloons Supermonkey series, and Bloons Pop!. They are typically created by attacks, by other projectiles, or, in Bloons TD, Activated Abilities, though they can also be created by other game mechanics. Most projectiles are weapons that inflict some kind of effect on Bloons on contact, such as dealing damage or inflicting a debuff, but they have a wide range of mechanics and uses and are not always used as such. Depending on the game, areas of effect, collectables, and objects placed on the track are also considered projectiles.
The radius of a projectile determines the size of its collision detection area. If a projectile has a radius of 0, it can only collide with Bloons if its center-point overlaps the Bloon. In the Flash games prior to Bloons TD 5, each projectile had an invisible shape attached to it (internally referred to as a hitbit) that determined its collision detection instead of a radius.
Some text, particularly upgrade descriptions, refers to the radius of certain projectiles as the "blast radius", especially for explosions. This refers to the same mechanic as projectile radius, though explosions and other areas of effect typically have very large radii relative to other projectiles.
Lifespan
The lifespan of a projectile determines how long it lasts before expiring on its own. Usually, projectiles have a lifespan of less than a second, limiting the distance they can travel (often only slightly more than the attacking tower's range). Some projectiles have very long lifespans, such as the projectiles placed on the track by Spike Factories or shot by Spike-o-pults, and others have very short lifespans, such as most explosions.
Speed
The speed of a moving projectile is how fast it travels through the air. Along with lifespan, this determines the overall distance that moving projectiles can travel before expiring. Stationary projectiles, such as explosions or those placed on the track, do not have a speed stat.
Offset
The offset is the relative position of a projectile from the centre of an entity.
In BTD6 Generation games, a tower's ejection point is almost always not exactly 0 relative to its own centre, due to the 2.5D nature of the game. Additionally, attacks with "sprays" of multiple projectiles side-by-side (e.g. Buccaneer's Double Shot) are actually offsets from an ejection point.
Angle
The angle is the anglular distance (e.g. 60°) between projectiles relative to an ejection point. An example is Ninja's Double Shot or Sub's Airburst Darts.
Random spread
This article or section needs more screenshots. See the screenshot guidelines for more information on what screenshots are needed and how to add them. The editor that added this notice elaborates: Image demo of projdev via distance or angle (try mortar and dartling)
The random spread, or projectile deviation, determines how offset the projectile will become compared to without it. Random spread can be relative by distance or angle. "Sprays" of projectiles can have both angular distance and random spread at the same time, such as Druid's thorns.
Pierce is the number of Bloons a single projectile is able to collide with. Typically, a projectile consumes one pierce per collision and expires upon consuming all pierce, though some projectiles consume additional pierce (typically when colliding with specific Bloon types). Some projectiles do not expire upon running out of pierce, but they cannot collide with any more Bloons if their pierce is exhausted.
Many projectiles deal damage to Bloons that they collide with. Some projectiles deal additional damage to Bloons under certain conditions, such as if the projectile deals extra damage to MOAB-Class Bloons. Some Bloons are immune to projectiles with certain damage types, such as Lead Bloons being immune to projectiles that deal sharp-type damage. Most projectiles expire instantly upon colliding with a Bloon that is immune to it.
