Deflation (BTD6)

"Start at round 31 with 20000 cash, but you can't earn any more."

- BTD6 introductory message to Deflation

Deflation is a mode in Bloons TD 6, returning from Bloons TD 5 but majorly altered. This time around, the player only starts off with $20,000 cash, or $20,200 if they have the More Cash MK point. All income methods are disabled, whether by pops, Banana Farms, Powers, or other sources. The player also cannot pay for Continues if they lose. However, selling towers does refund cash, and Insta-Monkeys are not disabled. Unlike in previous games, Deflation starts on Round 31 and ends on Round 60 instead of being endless, although the player can continue on in Freeplay Mode. When Round 60 is beaten, the player is awarded a special map medal and some Monkey Money. Completing Round 100 in Deflation for the first time will award the Inflated achievement.

Each Deflation option must be unlocked individually per map, by beating each map on Easy Difficulty in both Standard and Primary Monkeys Only. However, the Deflation property can be applied to any difficulty level in the Challenge Editor or Odyssey Creator.

The mode can also be played in Co-op, although it does not appear in Quick Matches. In Co-Op Deflation, the $20,000 (or $20,200) total starting cash is evenly divided between the players. In addition to the typical Deflation restrictions, the usual co-op ability to send cash between players is disabled.

Summary
Use the limited amount of money available to gather a defense that can beat all rounds between Rounds 31 and 60, meaning that a cost-efficient mid-game defense is required to beat Deflation. Low-cost, high synergy tower options are generally the best choice for Deflation, especially buffs from Berserker Brew and Stronger Stimulant. While not vital, Monkey Commerces help save money to squeeze in saved cash so that more defenses can be added in conjunction.

Tips

 * Useful heroes for Deflation include Gwendolin and Captain Churchill. Gwendolin is by far the most useful out of the three, as she provides support for any tower class type and can provide extra damage support for all towers in radius when she reaches higher levels. Captain Churchill, however, remains the most popular and can solo exceptionally on even harder maps, and is commonly used for tower XP farming.
 * Benjamin is much worse in this mode, as his money generating abilities don't work. Cyber Security and Biohack still function as normal, however.
 * Useful towers for Deflation Mode include 3-0-x Berserker Brew, 3-2-0 Destroyers (Destroyers with Hot Shot), 0-0-2 Monkey Commerce, 3-x-x Submerge and Support, 0-1-2 Ice Monkeys, 2-0-3 Triple Gun Subs.
 * Monkey Commerce is by far the most important upgrade for most successful Deflation Mode runs, especially when stacked upon other towers, but Monkey Commerce unfortunately only discounts the tower base costs and upgrades up to Tier-3. Successful players rarely would add Tier-4 upgrades to win Deflation Mode successfully.
 * The easiest way to beat nearly any map on this mode is to use two Villages (one 0-2-2 and another 2-0-2), two 2-0-3 Neva-Miss Targeting Aces, and one 4/0/0 Stronger Stimulant Alchemist. Due to Neva-Miss benefitting greatly from Alch buffing, it will easily wipe out the bloons on the track anywhere. This also works on tracks with multiple paths, moving tracks (such as Geared) or tracks with minimal space.
 * A 2-3-0 Robo Monkey and two 0-0-2 Villages next to each other with one Village upgraded to 0-2-2 alongside a tower that can pop Purple Bloons can complete Deflation Mode on all Beginner maps as well as most Intermediate maps and some Advanced maps.
 * One 0-2-4 Full Auto Rifle with 4-2-0 Stronger Stimulant and a 2-0-0 Village can easily solo Deflation on all Beginners, and can even solo Infernal.
 * A 2-0-3 Dark Knight along with 2 2-3-0 and 0-3-2 Triple Shot Monkeys respectively to help deal with Purple Bloons is also an effective strategy.
 * For tips regarding reaching Round 100 on Deflation Mode, see the strategies for the Inflated achievement.
 * Buy two 0-0-2 Villages next to each other. In range, buy a 3-2-0 and a 1-3-0 Dartling Gunner. Sell both villages to upgrade the 3-2-0 Dartling to 4-2-0. This should beat nearly any map with a clear sightline for the Dartlings.

Trivia

 * In version 6.0, 3 people beat the round 100 with a different setup for each.
 * Deflation Mode in a normal game disables continues by default. However, it is possible to use continues in Daily Challenges on Deflation Mode if continues are allowed.
 * This is only game mode to have different final round (60 instead of 40 like in easy mode).

Patched Strategies

 * Version 8.0 nerfed the price of Apache Dartship and Spectre to avoid players to hand-off win Deflation Mode.
 * Most strategies to hands-off win Deflation Mode were to use a 0-2-4 Monkey Ace (Spectre with Spy Plane), or a 4-2-0 Heli Pilot (Apache Dartship) in the radius of a 2-0-1 Monkey Village (Jungle Drums and Monkey Business), which both beat Deflation Mode on most maps.
 * In Version 9.0, Apache Dartship was price nerfed again from $19,500 to $19,600 on Medium Difficulty, preventing a single Apache Dartship to be placed on a normal Deflation Mode.
 * Prior to Version 28.0, 0-2-5 Elite Defender could beat all the maps on Deflation Mode, although it does require maximum Monkey Knowledge and precise placement and micro for harder maps. At the time, it was achieved by getting a 0-0-2 Village followed by a Sniper to 0-2-3, then selling the Village to get 0-2-5 Sniper, which still works to this day but lacks enough money for a lead-popping tower including a 0-0-0 Bomb.