How Bloons TD Was Made (Ninja Kiwi’s Story)

How Bloons TD was made starts in a small New Zealand studio in the mid-2000s and ends with a series that has been running for nearly two decades and shipped six numbered Tower Defense entries. Ninja Kiwi, founded by brothers Chris and Stephen Harris in 2006, launched the original Bloons in 2007 and the first Bloons Tower Defense the same year. The combination of monkey towers, balloon enemies, and clean Flash production became one of the most enduring browser game brands ever shipped.

Who Chris and Stephen Harris are

Chris and Stephen Harris are New Zealand-based brothers who founded Ninja Kiwi in 2006 in Auckland. Both came from web development backgrounds. The studio started as a small operation building Flash games and grew steadily over the following years on the back of the Bloons brand. The brothers have stayed associated with the company across the studio’s growth and have remained relatively private as public figures.

The New Zealand origin is part of why Ninja Kiwi stands out in the browser games space. Most prominent Flash-era studios were US or European; Ninja Kiwi built a global audience from a country that was rarely on the games-industry map. The studio is now one of the largest game developers in New Zealand by employee count.

The original Bloons

The first Bloons launched in 2007 as a Flash physics-puzzle game. The player controlled a monkey throwing darts at a field of balloons. The goal was to pop a target number of balloons with a limited number of darts, using trajectory and obstacles to chain pops. It was not a tower defense game; it was a casual puzzle in the lineage of Worms or Angry Birds (which postdated it).

The original was a hit by Flash-era standards. It hit the front pages of the major Flash portals of the time (which we won’t name) and accumulated millions of plays. The monkey-and-balloons brand became Ninja Kiwi’s signature, and the studio started spinning the format out into multiple games — a sequel, mobile ports, and an entry into a different genre.

The Tower Defense pivot

Bloons Tower Defense launched later in 2007. The format was already well-established (Desktop Tower Defense had popularized the modern web TD format earlier that year), and Ninja Kiwi recognized that the Bloons brand had a natural fit. Replace the generic creep enemies with balloons; replace the abstract towers with monkeys throwing darts. The mechanical logic is the same — towers along a path, enemies walking the path, money for kills, upgrades for towers — but the theme is unmistakable.

The first BTD was a small game by later standards: a handful of tracks, a few tower types, and a tight difficulty curve. It became another hit, and the studio committed to the series. BTD2 (2008), BTD3 (2008), BTD4 (2009), and BTD5 (2011) each expanded the tower roster, the bloon roster, and the meta-progression. The series became the studio’s flagship.

The Flash sunset

Adobe announced the end of Flash support in 2017 and discontinued the runtime at the end of 2020. Most browser-game studios of the era either died or pivoted hard. Ninja Kiwi pivoted: the Bloons TD series moved to native iOS and Android first (BTD5 had a strong mobile run starting in 2012), then to Unity-based desktop and HTML5 builds for the later entries.

BTD6 launched in 2018, built in Unity, with the full feature set required for a paid mobile game: cosmetics, hero towers, co-op multiplayer, and a steady update cadence. The migration off Flash is part of why the series is one of the few browser-game brands to survive into the 2020s with its audience intact. Most Flash-era TD franchises did not make the jump.

The design language

Bloons TD’s design language is distinctive enough that it can be recognized at a glance. Bright, cartoon-flat art. Monkeys with weapon archetypes (dart, boomerang, ninja, sniper, super monkey). Bloons in tiers (red, blue, green, yellow, pink, white, black, lead, zebra, rainbow, ceramic, MOAB-class). The progression up the bloon tiers — culminating in the MOAB, BFB, and ZOMG bosses — is one of the more readable difficulty escalations in tower defense.

The tower upgrades follow a clear two-track system in BTD6: each tower has two upgrade paths plus crosspaths, with the ultimate upgrades at the top of each path. The system is complex enough to reward deep strategy and simple enough to teach in-game without a tutorial wall. That balance is what kept the series accessible to new players across two decades.

The longevity

BTD6’s content cadence is a big part of why the series is still in the conversation in 2026. Ninja Kiwi has shipped frequent major updates since the 2018 launch — new heroes, new maps, new bloon types, new game modes, and a deep co-op multiplayer mode. The studio runs the game as a live service without aggressive monetization gates, which is rare in the mobile space.

The web presence has shrunk over the years. Most of the audience plays on mobile now, and the studio’s web portal mostly hosts older entries in HTML5 form. But the design DNA of the original 2007 Flash games is still recognizable in every entry. For a series-long perspective, see our history of Bloons Tower Defense; for the current state of play, our Bloons TD review covers what the latest entry feels like.

What it teaches

The Ninja Kiwi playbook is unusual for a browser-game studio. Hold the brand for two decades. Keep the design language consistent across major platform shifts. Ship a numbered sequel every few years that respects the audience’s prior knowledge. Run a live service without breaking the casual entry point. Most studios drift; Ninja Kiwi held its line.

The lesson for other developers is about commitment to a format. Bloons TD didn’t innovate the tower defense genre — Desktop Tower Defense already had the shape — and didn’t innovate the monkey-throws-dart mechanic. What it did was iterate on a single brand for nineteen years with discipline. That kind of patience is the rarer skill.

Frequently asked questions

Who made Bloons TD?

Bloons TD was made by Ninja Kiwi, a New Zealand studio founded in 2006 by brothers Chris and Stephen Harris. The studio is based in Auckland and is now one of the largest game developers in New Zealand by employee count.

When did Bloons TD launch?

The original Bloons puzzle game launched in 2007. Bloons Tower Defense — the first TD entry — followed later that year. The series ran through BTD2 (2008), BTD3, BTD4, BTD5 (2011), and BTD6 (2018). The Bloons TD Wikipedia entry tracks the full release history.

Is Bloons TD still free?

Older entries (BTD3, BTD4, BTD5) are still playable for free in HTML5 form. BTD6 is paid on mobile, Steam, and consoles but has been free during occasional promotional periods. The free browser entries cover the core experience.

What’s the best Bloons TD game?

BTD6 is widely considered the best in the series for depth and ongoing content support. BTD5 is the most beloved of the browser-Flash entries. BTD Battles (the PvP spin-off) has its own dedicated audience.

What’s a MOAB?

A MOAB (Massive Ornary Air Blimp) is a boss-tier bloon introduced in BTD3. It carries a large number of regular bloons inside it and survives multiple hits from most towers. The MOAB-class also includes the BFB (Brutal Floating Behemoth) and the ZOMG (Zeppelin Of Mighty Gargantuaness), each progressively tougher.

The takeaway

How Bloons TD was made is the story of two brothers in Auckland who shipped a Flash puzzle game in 2007 and have been iterating on the same brand for nearly two decades. The series outlived Flash, scaled to mobile, and is one of the rare tower defense brands still adding meaningful content in 2026. For a different kind of long-running browser game with a similarly disciplined design — one input, no upgrades, two decades of runs — the Chrome Dino game at the top of this site has been doing its own iteration since 2014.