Bloons Wiki
Bloons Wiki
BTDBM randomise dice

A pair of dice is an example of RNG. (Source: BTDBM "randomise" button icon)

RNG is an abbreviation of Random Number Generator. It commonly refers to game mechanics which have an element of unpredictability, usually governed by some code-based Random Number Generation algorithm. RNG or Randomness is present in Insta-Monkey selections, Late Game Round Generation, and most importantly, tower attacks as part of the damage types family. Examples include BTD6 Robo Monkey's Crits and Distraction.

In the context of the Bloons TD series, an attack consisting of RNG has a random chance of doing one outcome over another. Within Bloons Wiki, when an attack is tagged with Bloons Wiki's symbol for RNG, Involves pure RNG (unspecified types of RNG involved that isn't controllable at all by the player), depicted as the Randomize Towers icon in Bloons TD Battles Mobile, the attack relies on RNG for its power and cannot be adequately controlled by the player in any way shape or form, as opposed to Erratic Erratic Movement (unspecified variant) which can be amendable with proper positioning or upgrades that make the tower shoot more accurately (An example being crosspathing Rocket Storm with Focused Firing). In the example with Robo Monkey, it randomly crits after making between 15-20 hits, but the rate at which it crits cannot change because it relies on it making a random set number of attacks rather than positioning. RNG also applies with Distraction in two ways, the first and most significant example being the percentage chance of the blowback effect and the second and less significant example being the blowback quantity.

However, even though it cannot be directly controlled by the player, the player can minimize its effect. Taking Robo Monkey again as an example, it can be crosspathed with Plasma Blasts to increase its attack speed so it can reach 15-20 hits faster. Further buffs like Call To Arms and Overclock can also increase the Crit Frequency even more. Upgrading to The Anti-Bloon, the ability to Crit increases since the number of hits required to Crit has been lowered to 13-17 hits. Adding a Call To Arms or Overclock, and the RNG factor is mostly negligible. Most RNG is tied to attack speed and/or the number of Monkeys that have the upgrade because it is usually the main attack that is affected by the RNG. 1 Distraction Ninja might not distract a lot of bloons, but 20 Shinobi Tactics can almost distract at all times.

One could also argue that the Crits aren't even truly random at all. True RNG would mean that there would be some games in which Robo Monkey and higher upgrades wouldn't be able to Crit at all even if they shot all of the time because it just so happens that the player got unlucky enough to never Crit at all. The only "randomness" in Robo Monkey and higher upgrades is when they reached to their 15th shot (13th shot for The Anti-Bloon), the game decides when it should Crit. It's guaranteed by their 20th shot (17th Shot for The Anti-Bloon) that the Robo Monkey is going to Crit and it is also guaranteed that Robo Monkey won't Crit in their 1st-14th shots (1st-12th shots, for The Anti-Bloon).

Heroes Striker Jones level 5-18 making him can 50% chance to pop black and zebra bloons also count as RNG Involves pure RNG (unspecified types of RNG involved that isn't controllable at all by the player).

Upgrades and RNG[]

Upgrades with RNG[]

The following is a list of upgrades that involve RNG in their attacks, not including upgrades whose attacks rely on positioning (e.g. projectile deviation, on-track projectile placement, ricocheting behavior) rather than the outcome of hitting:

Upgrades formerly with RNG[]

Some upgrades formerly had true RNG attached to them. Others, such as Wall of Fire, have lost RNG by removing Erratic Erratic Movement (unspecified variant) behavior rather than a true RNG factor. This includes, but is not limited to:


  • According to Ninja Kiwi's 5th November 2021 blog, Ninja Kiwi states that certain in-game elements use "seeded formulaics" rather than pure RNG. One of their examples of tower attacks with "seeded formulaics" is Heart of Thunder. On the same blog, they claim that RNG is "bane of co-op [sic]".