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Tune up your Ninja senses: An Interview with the creators of iSlash

Even though I’ve created a game or two, I have to admit I don’t play them much.  But now and then I get caught up in playing.  iSlash by Duello Games is one of the few iPhone games that I’ve admired, played compulsively, and recommended to anyone who would listen. You can get a good idea of the gameplay by viewing the above video or, better still, downloading and playing the game.  According to Duello Games, there have already been 450,000 downloads, and the game has reached #1 status in Turkey, France, and Belgium.

Duello Games is located in Turkey, and consists of Ercan Caliskan and Benan Arıgil.  I was interested in writing up a review of the game and its strategy (hopefully in a future post), and reached out to them to find out more about the development of the game and their own take on things.  Here’s what I found out.

Tell me a little about your backgrounds.  The math grad seems to be the designer, the business grad is the developer

We always loved games and wanted to be part of that world. But 15 years ago it was difficult to have a career in this area. So we made what seemed logical decisions and studied programs that promised steady careers. But the love of creating something eventually won the fight and after graduation we pursued careers in digital media.

We were co-workers 10 years ago. Benan specialized in coding and Ercan specialized in design. Then Ercan went to USA and worked there for 6 years. Benan co-founded, now one of the biggest digital agencies, Rabarba and was the lead developer there. We designed and built interactive web projects, Flash games and adver-games.

But it was still difficult to make end user games and compete with million dollar companies like EA. Thanks to Apple and App Store, new doors opened to indie developers like us and we jumped on the bandwagon. Last May we quit our jobs and started our own independent game development company Duello Games.

Right from the beginning I noticed you guys were from Turkey.  Do you have any special advantages or disadvantages developing in Turkey?  Is there anything you want the world to know about Turkey?

One disadvantage is that there is lack of know-how when it comes to games.  There aren’t many game companies around. So you have to learn things by yourself and walk alone. Another disadvantage is it’s very hard to make your voice heard over in the USA. Our shouts get lost over the ocean 🙂 Even though our game iSlash got very popular here we couldn’t reach the majority of US game players, yet. One advantage for us is that we know a lot of people over here and we can easily market our games.

Have you developed any games before, either published games or hobby projects?

We’ve developed adver-games and flash games for brands.

Have your lives changed in any significant way, either as a result of building the game, or because of its success?

We are at the beginning of our journey. We haven’t seen a huge success yet, at least when it comes to sale numbers. But we are very happy that we are pursuing our dream of making games and we hope we never go back.

I noticed that the game was #1 in Turkey.  Any reason for that, given that the App Store is essentially international?  Are there other countries where you’re doing especially well?

The Turkish iPhone game market is a small one. Also we were good at what we were doing before, so people knew us. When we came with our first game there was a buzz around it. So all that helped the game to get into top 50. And after that it climbed to the top organically.

Where did you get the idea for iSlash?  How did it evolve?  Assuming that you were inspired by other games involving small bouncing balls that needed to be avoided, how far can you trace back the ideas?

You probably remember the games Volfied or Qix. (Qix has you drawing boxes on the field in order to capture as much of the playing field as possible. In iSlash, conversely, you slash away the playing field in order to keep the bouncing ninja stars trapped.) Those games are our initial starting point.

But we changed the dynamics a lot. We created new rules and made the game suitable for iPhone.

My other favorite iPhone game is called Surfacer.  A parallel concept, in that small bouncing particles will kill you if they hit you while you are taking away their space.  Are you familiar with it? The most fascinating thing about games like this is controlling and exploiting the “voids” created in a space of particles.

[a side note: as a tribute to Surfacer, I submitted a 1019-byte
Javascript version to the JS1K competition.  See
Don’t expect much – it’s only 1019 bytes of source code!]

We didn’t know about Surfacer. But we have seen similar games. There was one with blow fish. Same concept different skin.

Did this start off as a more abstract concept, with the ninja theme coming in as a skin? Or was that theme there from the beginning?

Actually the gameplay inspired the concept. Slashing reminded us of samurai. So we went with Asian theme from the beginning.

The sound design is very effective.  Was that done by a third party?  How much refinement went into it?  Are the sounds stock or custom?

Sound design was created by our talented musician friends from Dound Sesign ( All of it is original and made specifically for iSlash.

I have to say that the game makes sometimes me feel like a sumurai. Winning a board seems like I must summon all of my zen, kungfu and warrior powers.  When I am “on”, my cuts are elegant, and the world slows down. (Most of the time, of course, I am a total klutz.)  Did you work explicitly to achieve this feeling of timeless flow?

Yes, we spent a lot of time on level design. We went back and forth to fine tune it and make the gameplay a fun experience. The music helped us as well.

I like the post-game stats and map of cuts  Did you consider some sort of instant replay?

Yes, we are planning to have a replay feature in the future updates.

Was there a “less is more” philosophy to the design?  In other words did you throw out more elements than stayed in?  The absence of scoring, for example.

Definitely. We like less is more philosophy. The simpler the better. But we didn’t throw out a lot of elements. We had wire-frame designs from the beginning.

I like the way you build up the elements as you progress through the levels – metal edges, bombs and buddhas, red stars, ghosts.  Were there particular motivations for these?  Do they force or dictate any particular strategies?

All that was intentionally created to keep the game challenging and fresh. Metal edges bring strategy to the game. Red stars force you to act fast.

Did you explicitly decide to randomize the initial star positions for each board attempt? How would the game have been different if you had always set the initial star positions and velocities the same for each attempt? One con of the randomization is that sometimes the player is screwed from the beginning.  One of the pros is that the player cannot rely on learning a pattern, and must deal with randomness.  One interesting
element is that sometimes the player wins because of luck of the draw, although he must have the ninja-fu to exploit it.

Yes, we chose to go with random. As you have written, the randomness brings surprise and a chance factor to the game which makes it fun and addictive.

Are there any basic human instincts, emotions or skills that you are consciously trying to reach or exploit?

With new elements we feed curiosity. And since the game depends on reflexes it makes it addictive. When you fail you think “ohh, if I only waited a second I could have done it” and you play it again. Because you know if your reflexes are good you can win this time.

Innovation and good design often stem from, not so much total freedom but rather, a set of constraints.  Were there constraints to your development process that in the end made it a better game?

The iPhone itself has physical constraints. But also great features like touchscreen and gyro. So we designed our game to suit the device and it made it fun.

What was the hardest part of development?

Actually the hardest part was level design. It was hard to keep them balanced. Even now with the latest upcoming update we had to readjust the difficulty. There are a lot of people who finished the game in a day but there are more who got stuck on the final levels.

What was the most unexpected in terms of how the game turned out vs. what you originally set out to do?

Well, this was supposed to be our “hello world” game but it turned out to be a real game 🙂 Our plan was to finish it in a month and use it as a learning step. But it evolved, got better and better and became a game it is today.

How did you test this?  Did you have slow-motion versions, or automatic tests?  Or did you manually test at full speed?

We tested everything manually at full speed.

How did you set the difficulty?  I’ve gotten to various boards and considered them impossible.  Maybe that’s a good thing, because I’ve eventually beaten them, although perhaps only through good luck.  And of course, the board I’m currently on (the octagonal star) is impossible!  Have you guys manually played through all of the games?

We finished all levels a few times. But I guess we made the mistake of relying on our tests. We played the game a lot during development and got good at it without realizing. Also since we designed the levels we knew where to start and what to do to finish it. Next time we’ll have a larger pool of testers.

As mentioned earlier, with the next update we are readjusting the difficulty of levels. So you should be able to beat all with less effort.

Do you use any kind of formal process, or is it the usual kind of Agile?

We had a rough plan but it evolved. As I said before this game was supposed to be our “hello world” but it became “hello universe”. We still continue to revise our strategy as we learn new things and get new perspectives.

Is this your first game?

Yes, it is the first game we’ve created for the end user. Previously, we created flash adver-games for brands.

If I were to espouse a game development methodology it would be to find a fun mechanism or physics, and then set up puzzles to exploit the physics.  Do you guys have a philosophy?

We think in a similar way. Find a mechanism and build something fun on top of it. In our case we started with “swipe and slash” then it evolved.

How do you split the work?

Together we decide on the mechanics and elements but after that Ercan does the design work and Benan does the coding. But since we are two people we also have to build our website, do the marketing and all that.

What’s next?

iSlash HD for iPad is next. We are currently working on that. Hopefully it will be ready at the beginning of November and will support Game Center. After that we’ll start working on the second game. We have a few ideas but not sure yet which one will be the winner.

Are you guys gamers?

Yes 🙂

What games do you play the most?

Fallout, Star Craft 2, recently testing Play Station Move and of course iPhone games.
We normally like to play adventure ve rpg games but don’t have much time anymore.

What games do you admire the most?

Day of the Tentacle, Monkey Island, God of War.

What games have inspired you?

iPhone is a different environment where the majority of users are casual gamers. Popular games on iPhone tend to be different from other console games. So we can’t name any specific games that inspired us, but all contributed something.

In my day, videogame developers were far and few between – my guess is that there were less than a thousand.  These days, it seems everybody has been playing and writing games since they were seven years old.  There are probably tens if not hundreds of thousands of games out there, console, online, desktop, mobile.  On the other hand, there are now millions if not billions of gamers. Any thoughts on that?

It was difficult to become a developer back then. Now it is easier to access the information you need, thanks to internet and new technologies. But nowadays it is difficult to be noticed among thousands of developers and games.

I’d like to thank Ercan and Benan for taking time out of their busy schedule to answer my questions. They also answered some questions on strategy, and I’ll incorporate those into my write-up of the game and its strategy in a future post.

Duello Games just released a major update of iSlash, including an easier version of the board I’m currently stuck on.


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