Tomáš: We wanted to create a mix of tower defense and strategy games, where two people will play against each other, including attacking and other bit and bobs. Also, we wanted to create a web based game, which would be closer to serious gaming. And which could be played repeatedly, not just one time.

Me: Where can I get it or play it now?

Tomáš: The game can be played at www.ageofdefenders.com or can be downloaded from Android market and App Store. Also, it will shortly be available in App World. Age of Defenders runs on all tablets with the resolution of 1024×600 and up.

Me: How long have you been working on the original browser game and how big is the team?

Tomáš: We have started with a web version, which took us approximately 1 year. We are a team of 4 programmers and 3 designers. We have spent a lot of time thinking about the concept of the game.

Me: How many lines of code have you written for Age of Defenders?

Tomáš: Every single part of the game together, including the server-side code has around 110 000 lines of code. There are some libraries, which are not ours (e. g. pathfinding), but all of them are edited, so around 85% of the code is ours.

Me: Why have you chosen Flash/AIR for the development?

Tomáš: We liked the idea that you can play straight from the web browser, without having to download or install anything. That’s why using Flash was our first choice. Web-based gaming will change, will become something a lot more serious and we want to be part of this. Also the fact of building an app in Flash and porting it seamlessly to mobile devices with Adobe AIR later on, has proven how lucky choice it was.

Me: How long did it take to port it from iOS to Android with AIR?

Tomáš: When we had the first tablet version ready (iOS version), all we had to do for the other platforms was to work with the resolutions. The transition from the iOS to Android was very quick, took almost no time.

// Age of Defenders running on iPad, Sony S tablet, Sony P tablet, Windows and Samsung Galaxy Tab

Me: What are your next steps with the game and what features do you plan to add?

Vojtěch: Circ is a casual game for mobile platforms. We tried to create a dead simple game,
extremely easy to play, but still exciting.

The simplified main concept of the game is that you (rocket) circle around the planets, that constantly scroll down. By taping the screen, you can leave the planet and land on another. The trajectory of rocket is influenced by ‘force’ interaction of planets on you. You must avoid leaving the game area from top or bottom and score the best.

The whole game can be controled only by a thumb (on reasonably sized devices, of course) so this allows you to explore the game concept deeper and work on mastering the game even on your way to work, or school.

Me: Where does the original idea come from?

Vojtěch: The main idea behind the scene was to create a physical simulation of system of interacting particles just for fun. The simulation itself ended as so good eyecandy that I decided to combine it with game concept of one of my older games.

How did the design of the game evolve?

Vojtěch: At first, the game was very simple - as for the features, we tried to focus mainly on ‘force’ interaction between planets and player, which appeared to make the game very relaxing, without any need for extra bonuses, etc.

However, some of these features were also added later, as the game became more a ‘game’ than just a simulation. The very original ‘swipe-to-save-yourself’ feature has also been added at this stage. We had a bunch of ideas how to improve the feature base, but rather decided to freeze them at that point and have focused on publishing.

Me: Do you use DisplayList (Sprites) or Blitting and which rendering mode?

Vojtěch: We use DisplayList rather then Blitting in this case, rendering on gpu.

Me: How did you solve the challenge of multiple resolutions?

Vojtěch: The game package includes 4 variations of graphics of sprites and more than 10 various scales of background.

The device type is set in the begining and the whole game is created on basis of this. So in fact we have 13 scale and graphics settings for 13 different devices in one. By setting stage.scaleMode to NO_SCALE and stage.stageAlign to TOP_LEFT, we can decide during the runtime, which device settings to choose and rescale the application.

Me: What optimizations have you done to get 60 fps and what do you recommend?

Vojtěch: My advice is to be ecological - recycle and reuse.
I used pooling optimizations together with reference based data structures like linked lists instead of arrays/vectors.
This allowed me to gain from extremely fast splice operations, which are really common in game loop procedure.

It is also very important to avoid unexpected garbage-collecting during the loop phase of the application.
So try to keep the amount of created objects constant during the loop.

Me: Do you have any plans for the future development of the game?