C.H.I.M.P.S.

C.H.I.M.P.S. is a brand new game mode in Bloons TD 6. The abbreviation stands for "No Continues, no Hearts Lost, no Income, no Monkey Knowledge, no Powers, and no Selling", being "the true test of a BTD master".

Rules
C.H.I.M.P.S. is positioned in the Hard difficulty (but, instead of starting at round 3, starts at round 6 like in Impoppable mode), unlocked after completing Impoppable difficulty. Each letter stands for a certain rules and overall, the player is not allowed to:
 * Continue the challenge after they lose, meaning you cannot pay with Monkey Money to continue.
 * Lose any lives, only set to 1, similar to Impoppable, although no extra lives can be gained either
 * Gain money other than through popping bloons or getting money at the end of rounds. Banana Farms and other money generating towers become useless providing $0, and no extra money was received through any other means. However:
 * Before the 1.5 update, Monkey Town was able to give extra cash per bloon pop.
 * Before the 1.7 update, the mode did not give extra cash at the end of each round.
 * Before the 3.0 update, Druid’s “Jungle’s Bounty” Ability gave $200 everytime you activate it.
 * Currently, Obyn Greenfoot's Wall of Trees ability can give cash if bloons are captured, however it does not grant any extra cash other than what the bloon originally had.
 * Gain bonuses through the newly introduced Monkey Knowledge abilities and skill tree
 * Use Powers, such as Monkey Farmers, Portable Lakes, Monkey Boosts, Road Spikes, or Camo/Glue Traps
 * Sell their towers; towers are placed permanently and cannot be altered, except you can reposition them via Support Chinook. The Nature’s Ward Totem from Obyn Greenfoot cannot be sold either.
 * Note that if a Nature's Ward Totem is placed where a tower would be moved, it would be sold providing no money. This also applies to a Sun Temple or a True Sun God’s Sun Avatar spawns, also applies to a Marine from Special Popperations. Presumably, this would also happen if moved onto an Engineer's Turret when added.
 * Even though not mentioned in the description, Premiums are not allowed to be used.
 * Double Cash is among the banned Premiums, so avoid wasting real money trying to beat CHIMPS with Double Cash because it simply won't work.

Rewards
Beating any CHIMPS map will reward the same amount as would for Impoppable. However, this amount cannot be increased even if Mo' Monkey Money is unlocked in the Monkey Knowledge. Winning first time will also reward a small skull-shaped medal beside the Impoppable Medal. The skull can be red or black depending on whether CHIMPS is completed with or without loading the player's save game, with the black medal being regarded as "better".

If all medals are completed on a single track, the player is given a golden border around the track display border. Completing CHIMPS with the black medal will turn this border to a lustrous black color.

Tips
There are some useful tips regarding playing CHIMPS mode:


 * It's often the best choice to start off each CHIMPS mode game with 3 0-0-0 Dart Monkeys on different areas of the track, as they all have 2 pierce and decent attack speed to counter those early Green Bloons.
 * Pick towers that will be useful among all stages of the game and/or not cause a significant cost to the defense.
 * Using 3 0-0-0 Dart Monkeys at the start of the game is useful to start off each game, though it should be noted that some tower placements and/or tower boosts (especially Alchemist potions) may become less viable, so it is noteworthy to find Dart Monkey placements that are both able to defend the early rounds and not deal too much problems for later defenses.
 * It's worth saving money to place any essential towers when they are actually necessary for the defense.
 * If you spend too much money on defense, you will likely fall in a dead end as you'll have little leeway for potential alternate defense planning.
 * If you spend too little money on defense, you will likely lose too early and not likely acquire necessary Activated Abilities in time to defend against difficult rounds.
 * Alchemists, especially Berserker Brew and Stronger Stimulant, are popular towers that can assist going through middle-game (Rounds 40-60), late-middle-game (Rounds 61-80), and late-game (81-100+, though only beating Round 100 is required to win CHIMPS).
 * Memorizing significant rounds is necessary for winning CHIMPS. "Significant" rounds are rounds that both involve a turning point in strategical changes and/or a difficult change in bloon formation.
 * Rounds 6-15 and Round 17 are some of the few early-game traps that often cause inexperienced players to lose on.
 * Round 6 will have several Green Bloons and some Red Bloons on such an early round with only $650; very few strategies are able to defeat such rounds with such little cash.
 * Round 17 contains Regrow Yellows, rendering overly spaced or overly clumped defenses to struggle.
 * Round 24 has a Green Camo Bloon. Non-camo-popping defenses likely will lose on this round.
 * Round 28 has Lead Bloons. Lead-weak or non-lead-popping defenses will likely lose on this round.
 * Round 33, Round 36, and Round 37 are some of the other earlier Camo rounds to prepare for.
 * Round 33 has spaced Camo Yellows, Round 36 has Camo Regrow Greens in between a large wave of normal grouped Pinks, while Round 37 contains Camo Whites on the last wave.
 * Round 38 has the first Ceramics.
 * Round 40 has the first MOAB. The next MOABs appear on Round 50.
 * Round 42 contains Regrow Rainbows and Camo Rainbows, while Round 51 contains many spaced Camo Ceramics. Camo-weak defenses will likely lose on these rounds.

Update History
Nerfs and buffs listed here are in terms of causing more difficulty / less difficulty for the player attempting CHIMPS walkthroughs. Any "fixes" or any buffs or nerfs to other towers/heroes that cause very significant influence in improving CHIMPS walkthroughs are also listed here.

Overall, the CHIMPS mode has been nerfed.

Monkey Town no longer gives extra cash per pop.
 * 1.5

End-of-round cash is now earned every round.
 * 1.7

Jungle's Bounty no longer gives bonus cash.
 * 3.0

Unstable Concoction no longer causes affected MOAB-class bloons to damage its own children bloons.

Super Ceramics no longer give the same amount of cash as normal Ceramics.
 * 5.0

Alchemist's Berserker Brews and Stronger Stimulants no longer apply range buffs twice.

Stronger Stimulant now only lasts for up to 50 attacks or the same time duration of 15 seconds, whichever comes first.
 * 6.0

Berserker Brew now only lasts for up to 30 attacks or the same time duration of 7 seconds, whichever comes first.

Gwendolin's Heat It Up will trigger less often and will no longer refresh while Heat It Up is already in effect.

Trivia

 * The mode might be based on the common term NAPSFRILLS, which was commonly used in BTD5 that also have similar objectives, being unable to use agents, premiums, speciality buildings, farming, road items, lose lives, or sell a tower.
 * As of December 2018, the only tracks that remain to be completed on C.H.I.M.P.S. Mode are Muddy Puddles and Quad. As of December 2018, it is in fact impossible.
 * Players have so far not been able to pass Round 99 in Quad or Round 10 in Muddy Puddles.
 * This mode may be considered easier than Half Cash due to the amount of money gained is standard, despite its restrictions. Also, it is possible for C.H.I.M.P.S. mode to be impossible on a particular map. Half Cash is beatable no matter how hard the track is because Premiums, Powers, Monkey Knowledge, etc. are allowed to be used.
 * In most easy tracks, it is also easy to win without the need of extra income capabilities, Monkey Knowledge, Powers, premiums (continues, cash injections, etc.), without need to do any selling, or having to lose lives.
 * On the other hand, harder tracks are a lot more difficult to do without any of the forementioned benefits.
 * On Logs, If players place 1 Monkey Sub and 1 Super Monkey, it is possible that the towers can beat the entire track on C.H.I.M.P.S.
 * #Ouch CHIMPS used to be not solved after the Version 6.0 Alchemist nerfs. However, it was now solved officially on the official subreddit on Version 7.0 using the Comanche exploit. Link.