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A
- Acid Attack:
- The sixth game introduces the Alchemist tower, whose basic attack is throwing flasks of acid to deal Damage Over Time. Some upgrades allow it to throw stronger acid that deals damage faster, or create mini acid pools that damage bloons running over them.
- The Glue Gunner starting from BTD 4 can make their glue corrosive with an upgrade. Other upgrades can make the corrosion stronger.
- Allegedly Free Game:
- Downplayed for at least the normal BTD games. While there is a good bit of premium content for BTD4 and BTD5, you can play the game very well without them. The Steam version costs $10 and has only skins as premium content. BTD6 averts this, costing money to buy on both mobile and desktop (while retaining in-app purchases).
- Unlike the other games, Bloons Monkey City and Bloons Adventure Time Tower Defense are this trope. However, unlike most games, it very much is possible to play them without spending a single penny, but they will tell you about the premium items and currencies frequently.
- All Your Powers Combined:
- In BTD5, the Temple of the Monkey God will gain attacks and abilities related to all the towers sacrificed to it. For example, sacrificing a full power Ice Tower, Glue Gunner, Monkey Apprentice and Mortar will give the tower the ability to fire out exploding ice projectiles, corrosive glue blobs, giant tornadoes, and extra-powerful explosive missiles. All that along with the main Eye Beams.
- In BTD6, not only does the TotMG return as the Sun Temple, but there's an even stronger variant of it known as the True Sun God, which can power up even more with further sacrifices. This makes it a recursive example of this trope.
- Subverted by the Vengeful True Sun God. While it also sacrifices the two other tier 5 Super Monkeys, it doesn't gain either of their powers, instead only powering up its existing abilities.
- BTD6 also adds Paragon monkeys, which combine all the powers of their three Tier 5 upgrades and enhance them to absurd degrees. They also border on Infinity +1 Sword at some points, since like the Vengeful True Sun God, they need you to combine one of each Tier 5 to even create, on top of only reaching their full power if you sacrifice a boatload of the same type of monkeys that also have significant investment and pop counts.
- And I Must Scream: Presumably the eventual fate of a bloon, if left unpopped:"If you were a bloon, wouldn't you rather get popped instead of slowly leaking and withering to an undignified husk? I guess we'll never know since they can't speak."
- Animesque: The artwork of BTD5 has this look for some monkeys, especially the Ice Tower.
- Antagonist Title: The games are named after the Bloons, who are the enemies of the monkeys you play as.
- Anti-Frustration Features: Originally in BTD 6, when playing C.H.I.M.P.S. you could exit the game just before losing to salvage a run at the cost of receiving a less prestigious red C.H.I.M.P.S. medal instead of a black one. In update 42, they added a "Retry Last Round" option upon losing in C.H.I.M.P.S., which will automatically invalidate your black medal, but doesn't cost any Monkey Money or give you any extra lives or cash.
- Anti Poop-Socking: One round tip in the fifth game is "Remember to occasionally take breaks and do non-BTD5 things." The sixth game has its own variation of this.
- Appropriate Animal Attire: The Monkeys' choices of clothing cover the entire spectrum, from the completely naked basic Dart Monkeys, to the Fully Dressed Cartoon Animals like Quincy and Gwendolin. Usually, the higher the upgrade tier is, the more clothed the Monkey is. Notably, the series averts Pantsless Males, Fully-Dressed Females, like the explicitly female Adora wearing nothing but a cape.
- Area of Effect: Ice Monkeys, Bomb Shooters, and Mortar Monkeys all create some sort of splash effect. Upgrades such as Ring of Fire, Fireball and Razor Rotors add splash damage to other towers.
- Armor-Piercing Attack:
- If one considers Lead Bloons to be armored, which are impervious to sharp-projectile towers, only certain types of attacks can actually break the Lead layer. Usually these are upgrades involving explosives, fire, corrosion, or simply upgrading the dart material to something of heavier construction.
- Some upgrades do extra damage to Ceramic Bloons, such as Juggernaut for Dart Monkeys and Spiked Balls for Spike Factories.
- The Alchemist's Perishing Potions and the Mortar Monkey's Shattering Shells remove the Fortified effect from Leads and Ceramics (and the latter can even remove it from low-tier blimps).
- Arrange Mode:
- From BTD4 Expansion on, there is the Deflation mode, which gives you 50,000 money at the beginning, but disables all forms of income, and starts you off at round 30 (21 in BTD4 Expansion).
- BTD4 introduces the Harder Than Hard Apopalypse mode, which disables money income for progressing in between rounds, and removes breaks between rounds.
- BTD6 includes a set of modifier modes for each difficulty setting on a map, with the difficulty and variety of modifiers increasing on higher difficulties. The Deflation and Apopalypse modes are included among these, as are ones that restrict your available towers, Reverse Mode (which had previously been added to BTD5), Half Cash, Double HP MOABs, Alternate Bloons Rounds (a much tougher sequence of rounds), Impoppable (formerly its own difficulty setting), and the hardest of them all, C.H.I.M.P.S. (no Continues, no Hearts lost, no Income, no Monkey Knowledge, no Powers and no Selling). Beating all of these variant modes is required for gold-bordering or black-bordering a map, and some have to be beaten before others can be unlocked.
- BTD6 also introduces Races as a weekly event. Normally, a round only starts when the all the Bloons from the previous round are popped. In a race, however, the player can send the next round whenever they want. The goal of the race is to defeat all the rounds with as little time as possible.
- Art Course: In 6, the map Cubism
is based on the cubism art movement. The path forms zigzagging straight lines, separating the map into several areas, each with different colors. - Art Evolution: BTD2 and BTD3 used the same art style and assets as the first game, but the shift to BTD4 improved the graphics, and the art drastically changed for BTD5. BTD6 uses 3D models for the towers, some obstacles, and MOABs, and both Bloons Adventure Time TD and Battles 2 utilize the same 3D model style.
- Artifact Name: Towers named after the projectiles they throw tend to have an upgrade that makes them stop shooting the projectile they're named after.
- The Dart Monkey ceases to throw darts once they get the Spike-o-Pult (and Juggernaut after it).
- The Boomerang Monkey can exchange its boomerangs with Krull glaives.
- The Dartling Gunner stops shooting darts when upgraded to Tier 3 and above.
- The Tack Shooter ceases to shoot tacks when upgraded past Blade Shooter or Ring of Fire.
- The fan submitted map Erosion is a map based example. When it was first drawn it was based around water eroding sand. When it was officially made in BTD6 it was reworked into a melting glacier, which has nothing to do with Eroding.
- Art Shift: The purchaseable profile icons in the Trophy Store are done in different art styles than the main game. For example, Brickell's is a black-and-white manga drawing, while the Transforming Tonic one goes into Deranged Animation.
- Ascended Glitch: In BTD5, explosive towers that had their pierce buffed would increase the amount of time the exploding projectile could explode, rather than the amount of bloons the explosion could pop. While this bug was fixed on most towers, it persisted on the Hydra Rocket Pods of the Dartling Gunner. Come BTD6, and multi-explosion missiles are standard issue on the Rocket Pods, and is an explicit mechanic for Captain Churchill.
- Ascended Meme:
- In March 2019, a Biker Bones skin was released for Striker Jones. Biker Bones was a recurring joke name for Striker Jones on the BTD6 subreddit.
- In BTD6, the last Bloon to appear in round 5 of Alternate Bloons Round mode is a single Camo Regrow Red Bloon, in acknowledgement of the camgrow red memenote .
- In Update 17, after months of making jokes about the Cave Monkey in the Frozen Over map and asking how to free him, the developers added a method to free him, and even made him his own tower unique to the map. And true to his alleged power, he can stun any bloon except for a BAD—including a DDT or a ZOMG.
- A common joke on the BTD6 subreddit is "Player 3" in co-op games being money-obsessed, wasting their money on Banana Farms and refusing to give money to other players. The Scream emote for co-op introduced in 21.0 mentions that it can be used to scream at Player 3 for not sharing their cash.
- The "No Cash Drops" emote was spawned from complaints that players, most likely hackers, would repeatedly drop Cash Drops in co-op and end up making it way too easy.
- "2TC" (beat a game of CHIMPS with only two towers) and "2MP" (beat a game of CHIMPS with one tower getting at least two million pops) challenges are popular among fans, and later recieved their acknowledgements in-game, being added as hidden achievements.
- "Slons", a comically difficult fan-created joke map made for a contest, became a hit with fans. It got added as "Blons", with an identical layout, as a secret map in 24.0. This turned out to be an accidental content leak, as the way to access it was patched out so that Blons could be featured in an April Fools' Day daily challenge shortly after the update's release.
- Asteroids Monster: Basically the whole premise of the game, and which sets it apart from most other tower defense games: every single bloon except for the lowest tier has one or more bloons contained within it. Short list from strong to weak in BTD6: A BAD gives 2 ZOMGs gives 4 BFBs which give 4 MOABs, which give 4 ceramics, which give 2 rainbows, which give 2 zebras, which give a black and a white, which each give 2 pinks, and from then on only one comes out each time, going pink, yellow, green, blue, red. The other thing the BAD gives is 3 DDTs, which give 4 Camo Regen Ceramics. Additionally, there's also lead bloons that give 2 black and purple bloons that give 2 pink. Also, if a bloon gets through your defenses, you lose lives equal to the total amount of bloons you let slip (ceramic and blimp layers also count as lives lost), meaning that if a blue one gets through, you lose two lives, but if a ceramic gets through, you lose 104 lives. BTD4 added the Red Bloon Equivalent (RBE) counter, which is Exactly What It Says on the Tin—showing how many Red Bloons you are actually popping in the current round.
- Awesome, but Impractical:
- The Temple of the Monkey God in the fifth game is a little half-and-half. It fires enormous beams capable of tearing anything less than a BFB to shreds, but it costs a whopping $125,000 (on Medium difficulty without discounts), since you have to buy other Super Money upgrades to even access it (and that's without the range upgrades—counting those, the price goes up to $127,500). It will also sacrifice any player-bought towers in its range and absorb their powers, to the point of becoming powerful enough to down ZOMGs as though they were red bloons, but that means you need to pay for the absorbed towers (and you'll need a ton of money to get it to maximum power). Of course, this is normally only used in freeplay because of its high costs; although it is perfect for the rounds where bloons gain extra movement speed and health, there isn't anything forcing you to use it.
- Several of the tier 5 upgrades in BTD6.
- In general, the final upgrades for money-earning towers such as the Banana Farm and Merchantman Buccaneer are so expensive that you won't be able to make a profit unless you're going for the super-late rounds (or are doing Boss Bloons and need all the income per round you can get).
- Super strong, but very expensive tier 5 upgrades like Flying Fortress, Super Mines, and Ray of Doom. In a standard 100-round game, you can just sit back and wait for the victory screen after you purchase them. However, they're so expensive you'll never be able to get them without heavy farming. If you want to go into freeplay, you might as well get the Vengeful True Sun God or Paragons, which are more expensive, but also way more powerful.
- A Winner Is You: The messages you get when defeating the Bloons on a track and difficulty are this, with the most bland being whenever you win a map and difficulty that you've already completed in BTD6."VICTORY! You've stopped the nasty bloons[!]"
B
- Balance, Power, Skill, Gimmick: BTD 6 separates the towers into categories: the balanced Primary Monkeys, the powerful Military Monkeys, the skilled Magic Monkeys and the gimmicky Support Monkeys.
- Balloon of Doom: The so-called Bloons are the enemies that you need to defend the lanes from. Although considering the No Plot? No Problem! nature of the games, it's unclear as to why you're fighting them at all.
- Bee-Bee Gun: The Beekeeper, a Special Agent from the fifth game (and secret tower in the iOS version of the fourth), attacks by sending bees out of beehive to latch onto bloons for gradual damage.
- Beam Spam:
- Super Monkeys gradually get more beam-spammy as they upgrade, going from laser vision to plasma beams to the Sun God/Avatar (a Spread Shot of three sun beams) and culminating in the barrage of the Temple of the Monkey God. Then there's the Temple of the Vengeful Monkey unlockable ability, which lets the Temple shoot twice the amount of beams for a few seconds, and each beam is also more powerful.
- The Robo Monkey shoots two laser projectiles per frame (one per arm) to the Sun God's 1.5, though without as much spread or precision. Its upgrade, the Technological Terror, fires the same amount of beams as the Robo Monkey, but its plasma is green and extremely deadly: a single stream of this green plasma is twice as deadly as a single stream of the regular purple plasma, but since it fires two streams of it...
- The Dartling Gun's Laser Cannon upgrade makes it spam high-pierce laser beams. The following upgrades, Plasma Accelerator and Ray of Doom, turn it into a Wave-Motion Gun.
- Bears Are Bad News: The Beekeeper is a bear and aggressively attacks bloons with his bees. Good to know that he's on your side.
- Berserk Button: The Angry Squirrel, who goes berserk whenever a bloon leaks. His pro version gets a worse anger management problem, and it now gets pissed every 20 acorns it throws.
- BFG:
- Most military-based towers become one of these when fully upgraded, with appropriately powerful projectiles to fire from themselves.
- Big, Bulky Bomb: The icon for the Monkey Ace's Ground Zero and Tsar Bomba abilities have this. Using the abilities causes the Ace to drop a massive bomb that damages the entire screen.
- Blow You Away:
- In BTD5, the Monkey Apprentice gets this quite literally with the Tempest Tornado upgrade, allowing him to blow Bloons back towards the start.
- Downdraft on Heli Pilots blow bloons under the heli back to the enterance.
- In BTD6 the Druid of the Storm inherits the tornados of the Apprentice. The final upgrade on the Druid's top path even lets it blow back MOAB-class Bloons.
- Border-Occupying Decorations: Playing the Steam version of BTD5 at a wide aspect ratio gives the game a border with eight artworks of various towers.
- Boring, but Practical:
- Banana Farms are expensive and don't attack Bloons, but they give you extra money, which you will need in later levels when the Bloons themselves earn you less money. The Monkey Bank upgrade is more so this, especially in BTD6 with its Banana Farm nerf. This exchanges generating bananas and spewing them out for generating and storing money inside its own bank, which also has an interest rate, meaning the more money is in there, the faster you gain money (until you reach its maximum limit). In the sixth game, if you have a 2-3-0 Banana Farm, you can reach its maximum limit of $7000 within 12 rounds, making it an easy way to get money.note
- Starting a map with three dart monkeys. They might not be able to lead to many exciting upgrades, but it's one of the most versatile starts in the game, able to beat the first few rounds even on multi-path maps while leading to upgrades that can hold you out until something more powerful.
- The Glue Gunner. At first, it's a non-offensive tower which slows bloons, and isn't super-efficient at that, but it's so cheap that it can be placed early on to help other towers while conserving money. Putting enough into upgrading one allows it to either deal heavy damage-over-time to anything it coats with glue, spread glue across swarms of bloons and the entire screen that also increases the damage they take, or stop MOAB-class bloons in their tracks.
- The Spike Factory is simple and boring; no moving parts, just a constant stream of small piles of tacks. But it can be upgraded to pop lead bloons, there's a special option for ceramic bloons, and it can kill MOABs more quickly than a Super Monkey. The sixth game introduced the Perma-Spike, a fifth-tier Spike Factory that, even after some nerfs, still stands as one of the most useful fifth-tier towers despite doing nothing more than building a pile of high-damage spikes.
- Quincy in BTD6. He lacks the ability to apply buffs on other towers, like Obyn and Brickell, and can't debuff bloons either, like Gwendolin, Ezili, and Benjamin. Even among the pure DPS towers, he hardly stands out, with Adora's sacrifices letting her reach her maximum potential early on (and endgame act as a Sun Temple/True Sun God buffer), Etienne drone swarm allowing for attacking out of line of sight, and both Sauda and Churchill sporting more raw power. However, Quincy is one of the only heroes capable of starting a game, greatly aids during early rounds, and holds reasonable damage output even in late-game.
- Boss Battle:
- Not formally called as such, but the rounds 40, 60, 80, and 100 invoke the feel of a boss battle, as each only consist of a single MOAB-class Bloon which is stronger than any Bloons you've faced in the previous rounds.
- Boss Bloon events are a more traditional take, replacing the MOA Bs on rounds 40, 60, 80, 100, and 120 with an increasingly powerful Boss Bloon.
- Boss-Only Level:
- A few rounds in the series have rounds in which only MOAB-class bloons (or other high-ranked bloons) appear.
- Averted by the actual Boss Bloons, which appear alongside the bloons of further rounds.
- In BTD5, there is only one bloon in Levels 46, 60 and 85—the MOAB, BFB and ZOMG, respectively, which are introduced in said levels. Not the case for the latter in Impoppable difficulty, as you face five ZOMGs in Level 85.
- The ending rounds of Easy, Medium, Hard, and Impoppable/C.H.I.M.P.S. difficulties in BTD6 are fights against a lone blimp. Easy has the MOAB on round 40, Medium has the BFB on round 60, Hard has the ZOMG on round 80 and Impoppable and C.H.I.M.P.S. have the BAD on Round 100.
- In Alternate Bloons Rounds, round 100 is a single fortified BAD.
- Round 200 in freeplay is a special non-random round made of 2 fortified BADs
- Boss Rush:
- Level 75 of BTD4, the final level of Hard mode on any course, is a long sequence of MOAB and BFB bloons and nothing else.
- In BTD5, the final round on Impoppable difficulty has not one, but five ZOMGs.
- Round 98 of BTD6 sends out 8 ZOMGs and 30 fortified BFBs.
- Freeplay rounds from BTD4 onwards are essentially waves of nothing more than bigger, faster, and tougher waves of blimps. In BTD5, for example, later Freeplay rounds are immense waves of nothing but ZOMGs, while BTD6 gives a bit more variety thanks to the existence of the BAD, DDT, and the Fortified modifier.
- Bowdlerise: The Cool Math Games version of the first game changes a pre-round message about the Super Monkey from "he really kicks ass!" to "he is really poptastic!".
- Bread, Eggs, Breaded Eggs:
- Black Bloons are immune to (most) explosives, White Bloons are immune to freezing, and Zebra Bloons are immune to both of these!
- The pre-round comment for Round 59 in BTD6 has this with leads and camos."Can you pop Lead? Can you pop Camo? How about... Camo Lead?"
- An unofficial term for Bloons that have both the regrowth and camo properties combines the two into "camgrow".
- Bribing Your Way to Victory:
- In the fifth game, there are a lot of options for outright breaking the game for the payment of real money. They range from simple upgrades, such as dart monkeys getting an area of effect on the dart, which simply give towers more versatility or firepower, to buying ingame money (both Monkey Money and the cash required for upgrading towers) as well as lives.
- The sixth game has the double cash mode from the fifth game, now costing 18 dollars instead of 10, and you can still buy Monkey Money, but you can also buy Insta-Monkey packs, which are pretty much this game’s version of loot boxes. Just like BTD5’s in-app purchases, however, they are entirely unrequired to enjoy the game. In fact, Insta-Monkeys are also given out rather generously through collection events, and double cash is the only thing you can't get through just playing the game.
- BTD6 also brings the "Unlock All" ability, which instantly gives you all the upgrades for a selected tower. While they only cost USD $4.99, you can easily farm the XP needed for the upgrades. All real money purchases are rendered null by the CHIMPS difficulty modifier, which levels the playing field some.
- Bullet Seed: The Watermelon Spitter Special Agent, a chipmunk that builds up watermelon seeds in its cheeks and spits them out as soon as bloons enter its range.
C
- Call-Forward: The map Village Shore in BTD5 is a reference to the main menu◊ of BTD6. Note that this map was released exactly one month after the release of 6.
- Cap: The fire rate of any tower cannot exceed once per frame. This makes Overclock and MIB Call To Arms useless on towers with certain upgrades (such as the Ray of Doom for the Dartling Gun, Technological Terror for the Super Monkey, etc.). Even worse (but possibly funny) is that towers that are (somehow) overclocked too much deal no damage to any kind of bloon!
- Cast from Hit Points: In Bloons TD 6:
- The Bomb Blitz and Elite Defender passive abilities require the player to lose lives to activate them after cooling down.
- Ezili's Sacrificial Totem ability, which temporarily buffs nearby towers and grants them camo detection, costs the player lives each time it is activated. It will cost less lives the higher Ezili's level.
- The Druid's Heart of Vengeance grants extra attack speed for each life lost. This bonus will disappear if the player heals their lives after a leak.
- Challenge Run: Many of the game modes involve special restrictions and rules:
- Apopalypse (no breaks between rounds, no end-of-turn income)
- Deflation (you start with a large amount of money, but can't earn any more)
- C.H.I.M.P.S. (only one life, no powers, no Monkey Knowledge, Money Multiplier towers don't work, and you can't sell towers)
- Single-class runs (Primary only, military only, magic only)
- Double MOAB health
- Half-cash
- The daily challenges and advanced challenges offer a new set of rules each day, usually by limiting which towers you're allowed to use.
- Odysseys require you to complete 3-5 maps with a specific set of Monkeys.
- Boss Bloon events see you face off against a Boss Bloon, putting your skills to the test.
- Changing Gameplay Priorities: In early rounds, you want to prepare against the various types of Bloons the game throws at you. As stronger Bloons can pop into multiple weaker Bloons, towers that can pop many Bloons at once are favored. In later rounds, however, piercing is no longer an issue and your main concern is having as much damage as possible against Ceramics and MOABs, because the game will start throwing a bunch of them. This gets exacerbated by the appearance of Super Ceramics, which are much tougher than regular Ceramics but only have one child.
- Character Select Forcing:
- It's impossible to win BTD2 without Cannons, because they're the only towers in the game capable of popping Lead Bloons.
- Flooded Valley is a map largely covered in water, separated from the land by a large wall. If you're going to use a hero for this map, it's going to be either Admiral Brickell or Pat, as both can be placed on water, with Brickell also syngerizing well with water towers. While Adora's ability briefly gives her enough range to attack up the wall (and thus is the go-to for Primary Only on this map without using pontoon powers), it's rather inefficient, and Churchill is too expensive to be feasible despite his large range.
- Spillway encourages CHIMPS players to start with a Ninja Monkey, since it's the only starting tower that is both small enough to fit in the middle barrel that allows it to attack bloons entering the track's middle circle, and can pack a decent amount of early popping power. The middle circle is surrounded by expensive-to-remove walls and a moat that hinder all other towers from reaching inside.
- Daily Challenges, Odysseys, and Races will often only let you use a certain selection of towers or heroes.
- Checkpoint Starvation:
- The Flash version of Bloons Tower Defense 5 did not allow you to save on Extreme-difficulty tracks. However, the mobile version permits saves there.
- Usually, Bloons TD 6 autosaves after finishing any round except in Co-op, deleting the save upon death, a forced restart, or switching to a different mode on the same map. However, Hard Mode in the "Happy New Year's" Odyssey had merged sequences of up to eighty rounds into one round per island, meaning that if you exited an island for any reason, you had to restart the entire island from the beginning.
- Chuck Cunningham Syndrome: Almost all the Special Agents in Bloons Tower Defense 5 do not return in 6, with only the two monkey-based Agents persisting over.
- Color-Coded for Your Convenience: In BTD6, towers are divided into four categories, with each category having its own color, as well as another category for heroes. Primary is blue, Military is green, Magic is purple, Support is orange, and Heroes are yellow.
- The Computer Is a Lying Bastard: The description for the Mortar Monkey's Artillery Battery in BTD5 says that its "Pop and Awe" ability doesn't affect MOAB-class bloons. Yet, it still stuns them against what the description says, though the stun is weak on anything stronger than a MOAB.
- Computer Virus: At level 7, Benjamin, the Code Monkey hero in BTD6, writes Bloon trojan viruses, and when successfully sent to a Bloon, causes them to spawn no children (the Bloons in lower layers) when popped. The downside to this is that you don't get the money from them. This was eventually changed so that you receive the number of layers the bloon has in cash (so an infected rainbow bloon, having 8 layers, gives $8 upon being popped), so you get back something from popping it. You still lose out though.
- Contractual Boss Immunity:
- In the early games, MOABs and BFBs are immune to slowing down as well as the Super Monkey Storm (otherwise a One-Hit Kill). Later games would introduce more ways to slow and stun MOAB-class bloons, though these are typically reserved for high-tier towers.
- In BTD5, there are a few special abilities which do nothing except for destroy a single MOAB-class bloon. However, the ZOMG, while not completely unaffected, will only take 1000 damage. When the sixth game introduced a tougher blimp, the ZOMG became So Last Season and some towers got upgrades that could instantly kill it.
- The BAD from BTD6 is immune to all kinds of slowing or stun status. Other debuffs (such as debuffs that cause bloons to take extra damage from getting hit, such as Cripple MOAB, Super Brittle, and Glue Storm) can still affect it, though.
- Cool Airship:
- The MOAB-class bloons are various blimps with acronym names that serve as Bosses in Mook Clothing. There are five different types of them as of the sixth game.
- The boss bloons, which were first introduced in the fifth game, use the same design format as the MOAB-class bloons with even more stylish aesthetics.
- Cool Boat: Two water-based towers exist in the games. The first introduced was the Monkey Buccaneer, a mid-price tower that can be upgraded into a fast-firing battleship that controls miniature fighter planes, an explosives-armed, grape-shooting pirate ship that can hook onto blimps to instantly kill them, and (starting in the sixth game) a merchant ship with massive income bonuses. The second is the Monkey Sub, which is cheap and initially weak, but can get an Advanced Intel upgrade to let it fire darts at bloons in the range of any towers. Its upgrades include a nuclear submarine that melts bloons in its radius (the sixth game lets it become an Energizer that reduces tower cooldowns and increases hero experience gain), a missile-bombarder with an ability that can One-Hit Kill a ZOMG (further upgradeable to let it fire strong missiles at any blimp entering the screen), and a Sub Commander that can boost the strength of an armada of subs.
- Cosmetic Award:
- There are hidden achievements in BTD6 that enable access to Big Bloons, Small Bloons, Big Tower, and Small Tower mode, where Bloons/Towers become bigger/smaller than usual. However, this is purely visual, as the Bloons/towers still retain their original hitbox.
- The Trophy Store of BTD6, where you can exchange trophies obtained from Races and Odysseys for things such as player avatars, new music, new special effects, Bloon skins, etc. Items bought at the Trophy Store are entirely for cosmetic purposes and don't alter the gameplay.
- Crossover: In Bloons Adventure Time TD, the Bloons invade the land of Ooo!
- The Cracker: Benjamin, the sixth hero in BTD6, zigzags this. While he is a hacker who can create viruses, he's on your side and is happy to use his skills to get you more money and sabotage the Bloons.
- Creator's Pest: The series has quite a few of them.
- The infamous Bloonchipper. It's a woodchipper that sucks in Bloons to pop them that appeared in the BTD5 Generation. It was infamously a nightmare to balance (being extremely overpowered with the ability to stun and do massive damage to MOAB-class Bloons). When it was not added into BTD6, many people constantly requested for it to return, with Ninja Kiwi adamant it stays out of the game. It was eventually added to the game in 31.0... broken down and left to rot in a scrapyard.
- Arctic Wind ice platforms, from the x/3/x Ice Tower have become despised by Ninja Kiwi for the sheer number of glitches and bugs that they were responsible for (including multiple infinite cash exploits).
- Legend of The Night's Black Hole passive could be considered one, since it could be used to cheese and get through infinite rounds without dying. Ninja Kiwi has nerfed this ability multiple times to make it unable to do so.
- Crutch Character:
- Dart Monkeys in BTD5 upgraded to Triple Darts are very effective early on, but become far less powerful later in the game.
- Monkey Engineers with the Sentry Gun upgrades are so cost-effective early game that one of the most common early-game builds in BTD5 is just to rely on that for the entire early game in order to farm money. Without Cleansing Foam, however, they can't do anything about Camo or Lead bloons. Engineers can remain useful throughout the game just for the sheer area they can cover, though they start to fall off in usefulness against MOAB-class bloons (unless you're positively covering the map with them).
- Dartling Guns are one of the more useful towers as-is and can cheaply mow down all but the most thick clusters of bloons with some upgrades, especially with some good placement. However, once the first MOAB-class bloon shows up, they notoriously struggle to deal enough damage to the blimp layer fast enough to make a difference. This can be subverted with sheer numbers of Dartling Guns or several of the highest upgrades, though it would cost far more than just using towers better suited to MOAB-busting baseline.
- Sauda is like a souped-up Tack Shooter who can be bought on Round 1, has very fast attacks, has camo detection, and can pop lead bloons with her abilities. On maps that contain long bends or loops, she can solo the first 27 rounds AFK, and some players have completed 1-tower Impoppable and even CHIMPS with just Sauda. However, on harder maps with split tracks and less loops, Sauda's lack of range becomes an issue and her effectiveness drops down considerably.
