🎮 Overview & Release

• Developer/Publisher: Ninja Kiwi

• Release Date: October 26, 2009, originally a Flash title (BTD4 HD later on iPad).

• Platforms: Flash browser, iOS (2010), Android/HD versions, handhelds like Nintendo DSi, PSP, PS Minis.

🆕 New Additions

• Towers & Road Items: Added six core towers—Glue Gunner, Monkey Ace, Mortar, Monkey Apprentice, Banana Farm, Monkey Buccaneer—plus Dartling Gun and Spike Factory later.

• Bloon Types: Introduced tougher and varied bloons including Camo, Pink, Zebra, BFB, MOAB, and more.
• Modes: Career, Sandbox (unlimited money/lives), Apopalypse (non-stop waves).

🗺️Maps & Difficulty

• Tracks: 9 free maps (3 Beginner, 3 Intermediate, 2 Advanced, 1 Expert) and 8 premium maps purchasable with NK Coins.

• Rounds: Vary by map and difficulty—easy (~50 rounds), medium (~60), hard (~75).

🔝 Gameplay Mechanics

• Progression: XP-based unlocks by popping Bloons.

• Tower Upgrades: Four-upgrade tier per tower, with enhanced paths (Spike Factory from Dart, Dartling Gun).

Strategic Tools:

• Monkey Beacon: Boosts attack rate, leads detection, even screen-clearing storms.

• Banana Farm: Passive income tower on completed rounds.

👍 Reception & Legacy

• iPhone review praised its addictive gameplay and polished presentation, calling it a refreshing take on TD games.

• Often cited as one of the most refined entries in the series, merging variety with simplicity.

🧠 Tips & Tricks

• Use Tower Specialties to optimize your strategy per map or mode.

• Place banana farms early in career and Sandbox, but avoid in Deflation mode.

• Combine Glue + Mortar/Ace to slow and burst heavy bloon waves.

• On Monkey Temple map, unlock Sun Temple via sacrifice for major power spike.

• Try Apopalypse Mode for continuous challenge and grinding XP.

📌 Summary

BTD4 significantly expanded the Bloons formula: it introduced new towers, bloon types, game modes, and strategic depth.

The Expansion pack further added specialized challenges, modes, and strategic variance.

It’s a beloved classic bridging the simple charm of early Bloons titles with richer, more refined gameplay.