Bloons Tower Defense Battles

 is the multiplayer, competitive version of Bloons TD 5, with different strategies, tracks, and features. In this game, players use their money to send bloons (Assault Mode only), purchase income boosts (Defend Mode only) and build towers, with 150 lives at the player's disposal to defend against both consistent, computer-generated bloons and, if playing in Assault Mode, unpredictable bloons sent by their opponent.

A Ninja Kiwi account is required in order to play this game on the computer.

The Main Menu of Bloons TD Battles has 5 options:
 * Quick Battle: Searches for a random opponent to play against.
 * Private Battle: Lets the player create battles and join battles created by other players, but only if the Battle ID is known by the joining player.
 * High Scores: Checks the leaderboard for the highest battle score.
 * Towers & Bloons:
 * Towers and their Tier 4 upgrades can be purchased here using Medallions.
 * Bloons Decals, essentially decoration for bloons, can also be purchased with medallions.
 * Store: Brings up the Store, similar to the Premium Store in Bloons TD 5.

Bloons

 * All bloons have an income change, either increasing or decreasing (or neither) the player's only initial source of extra money besides Banana Farms in the game, a 6-second income boost.
 * Thus, as the player obtains no money from popping bloons, it is important to constantly improve their income by sending bloons which increase the most income for the lowest cost.
 * In Defend Mode on the other hand, the player's only way of improving their income is by purchasing periodic income boosts.
 * In assault mode, you start off with $250 income, and $650 right off from the get-go. This means that you will get $250 per 6 seconds. By spending money to send out bloons at your opponent, you can increase the amount of money you get every 6 seconds. For example, if you send out 8 grouped red bloons, your income will increase by $1.
 * As rounds progress, stronger and stronger bloons get unlocked, meaning that you will have to constantly improve your defenses. For instance, spaced Pink Bloons are unlocked on round 4, and spaced Black Bloons are unlocked on round 6.
 * Bloon sends can be Regenerating or Camo. These modifiers are unlocked on round 8 and 12 respectively. Changing bloon types this way will incur an additional multiplier on the cost of the bloon. For instance, the cost multiplies by ×1.8 and ×2 respectively, or ×3.8 if both are applied. MOAB-Class Bloons are unaffected, but their non-blimp children spawned are.

Towers

 * Upon playing the game for the first time the Dart Monkey, Tack Shooter, Sniper Monkey, Ninja Monkey and the Bomb Tower will be unlocked. Note that their Tier 4 upgrades are locked, and must be purchased with medallions.
 * The next towers, which are unlocked upon reaching a 50, include the Ice Tower, Boomerang Thrower, Glue Gunner and Monkey Buccaneer. Unlike the towers you get from the start, you must pay a small amount of medallions (usually 10-20) to even be able to use them, as well as additional medallions for their respective Tier 4 upgrades.
 * The third tier of towers are unlocked upon reaching 250. These are the Monkey Ace, Mortar Tower, Spike Factory and Dartling Gun. Again, they must be purchased for use in battling along with the separate Tier 4 upgrades.
 * The final tier of towers, unlocked upon reaching 500, include the Super Monkey, Monkey Apprentice, Monkey Village and Banana Farm.

Rounds
Rounds are mostly the even-only equivalent of those in Bloons TD 5, with only a few exceptions. For instance, Round 43 represents Round 85 of BTD5 instead of 86, and Round 12 that is Round 25 of BTD5 instead of 24. However, in the iOS version, Round 12 is Round 24 of BTD5 instead of 25.

A round only begins 4 seconds after one player has popped all computer-generated bloons in the previous round, or 8 seconds after all the natural bloons have been spawned, whichever occurs earlier.

Other features

 * 1 is recovered every 12 minutes.
 * Medallions appear to be much like the Bloons TD Battles version of the Bloons TD 5 Monkey Money used to buy Towers and Bloon Decals in the Shop/Towers & Bloons menu.
 * The player earns 2 for losing, and earns 5 for a win.
 * 10 is awarded for winning. Losing rewards 2.
 * There are 2 "abilities" to use during the thirty-second time before battles: the spy and an extra tower slot. The spy costs 3 and lets you see the opponent's towers and the extra tower slot costs 6 and lets you choose 1 extra tower for a total of five towers
 * In the mobile edition, the bonus is chosen randomly by a roll and can be any tower, even towers you didn't yet unlock. Rolling costs 1 energy and rerolling costs 3.
 * The player can choose between Assault and Defensive Mode.
 * In Assault Mode, the player attempts to crush their opponent with bloons, similar to the Bloons TD Battles before the update with defend mode. After Round 30, all player-sent bloons will have their speed boosted by 20% each wave.
 * In Defend Mode, the player attempts to outlast their opponent. They cannot send any bloons, and have an initial income of $60. It can be increased by purchasing income boosts, which have a cooldown based on the income increase; the higher the boost, the longer the cooldown, but also the more cost-effective the boost is. Income is capped at $3,000.
 * Small income boost - Increases income by $2. Cost: $50. Takes 150 seconds to "break even", as in, pay for itself.
 * Medium income boost - Increases income by $15. Cost: $300. Takes 120 seconds to break even.
 * Large income boost - Increases income by $70. Cost: $1,000. Takes approximately 90 seconds to break even.
 * Huge income boost - Increases income by $700. Cost: $7,500. Takes approximately 66 seconds to break even.
 * MOAB-class bloons gain 20% speed and 40% health per wave after round 30.
 * Selling towers returns 70% of the purchasing price rather than 80%.
 * In-game chat and the Dartling Gun were added to Bloons TD Battles in the same update that added the track Hydro Dam to the game.

Video
What is BTD Battles?