Stephen Harris is the co-founder of Ninja Kiwi, a developer and publisher of flash web games and mobile games. He started Ninja Kiwi in 2006 with his brother Chris. Ninja Kiwi recently acquired Scottish mobile gaming studio Digital Goldfish, which increased Ninja Kiwi’s number to 34 full time people. As a game-maker, here are some of Stephen’s insights into how Bloons Tower Defense was created.
Bloons Tower Defense is a flash web game. We made it when it was just myself and my brother in the company back in late 2007. We took our popular Bloons game idea and worked a tower defense game around it. It was pretty successful straight away so we made a sequel, Bloons Tower Defense 2. A few months later we made Bloons Tower Defense 3 – and that became the first mobile version which was simply called Bloons Tower Defense. This is where things get kind of interesting! Bloons TD4 took much longer to make than the previous ones, given that the competition for eyeballs in the flash gaming space was really starting to ramp up. Production value and length of play was increasing all the time. Add to that our pride to make BTD4 much much better than the previous ones. It took many months but our small team put it together and it was a massive hit. I did all the coding and most of the game design but by then we had a full time artist to help make it look awesome. When it went over to mobile we knew the strength of the brand “Bloons TD4” was so strong that we had to call it that on mobile even though it was technically only the second BTD to go to mobile. It was a huge hit on the iPhone. I was somewhat creatively drained after btd4 so we waited a full year before starting on the next one (did other projects in between). The bar was pretty high at this point so there was huge pressure to make it bigger and better in every way. Luckily by then we had expanded our staff enough to be able to really get some quality in. December 2011 we finally got the web version out and it was again an instant hit. One year later it came out for iPhone, getting to #2 on the US charts inside of 9 hours with no Apple feature.
Each iteration of Bloons Tower Defense has been bigger, bolder, deeper and just plain better than the previous. Each version of the game has had innovations that made it stand out from other contemporary TD games, but each time it has become more difficult to come up with new stuff that people will find fun but is also innovative and interesting to work on. Early versions of BTD introduced “on track placeable” items like road spikes and monkey glue which allowed players to have more direct control over how and when they pop bloons, and to get them out of a sticky situation. Bloons TD4 introduced terrain specific towers (the monkey buccaneer) and moving/flying towers (the monkey ace). In Bloons TD5 we introduced tracks with dynamic moving parts, tunnels, special missions (with unique and interesting rule sets) and activated abilities (powerful abilities with cooldowns that are activated when you choose). In addition we added stuff like special agent towers, monkey lab upgrades and tower specialty buildings. Specialty buildings and Monkey Lab upgrades were a way for players to further customise and really own their BTD experience.
The original BTD aesthetic was based off of the original Bloons puzzle game art, which my brother Chris drew. That art style, although a bit dated and clumsy drove most of the brand for several years. By the time we made BTD4 it had evolved to a much slicker look, but still with those roots. For BTD5 we decided it was time for a fresh look. We wanted the art to remain bright and friendly, but it was time for the monkey to lose a few pounds (he was kind of round). We had Tamihana (artist) draw a few tower and monkey concepts and we finally settled on the current look. The rest of the game and the interface just followed from that look.
As a player, I love finding new tower combinations that work well unexpectedly. I love that even when I’ve played the game 100 times in 24 hours and I’m sick of it yet I still really have to test this one thing, I still end up just playing to win. As a designer, I love that everyone who likes the game feels their strategy is the best or that they have learned some secret knowledge on how to beat the game. The true secret is the game is actually pretty easy and all the towers are designed to be fun to play and to essentially kick butt, at least on the easier difficulty settings. The trick is to make the game feel like it’s really working you over pretty hard, but that you can still prevail.
We wanted to deliver masses of content and awesome stuff and basically just blow people’s socks off. From BTD4 we went from 4 upgrades per tower to 8, including the all new activated abilities. That said, regarding towers at least, I thought that might be enough and that adding new towers for new towers sake might cheapen the whole game. I realised though that the perception for our fans would be that we were lazy because we didn’t add new towers, and that they would not enjoy the depth of the game until they’d played it a fair bit (all 8 upgrades per tower). So I came to my senses that we needed at least 2 new towers. We added the Sniper and the Ninja Monkey, both of which are among the most popular and are now firmly rooted in the Bloon TD world. No one on the team was particularly pleased at this huge scope creep, but it was the right decision.
The original Bloons game concepts (in 2007) just had a disembodied dart and aiming arrow used to shoot bloons. Towards the end of the game development we threw in a character just to make it look more friendly, and naturally chose a monkey. The notion of monkeys popping bloons just exploded from there I guess.
I think BTD5 will continue the legacy of the Bloons Tower Defense series as a leader of the genre, at least regarding web and smart phone games. There are several notable tower defense games that are right up there (Kingdom Rush, and the exceptionally awesome Plants vs Zombies to name two) but I still feel BTD5 adds so much more content, depth and value than any other. I also believe our innovations in the genre often become standard for other TD and defense games that follow.