[This is a guest post by Justin Smith, who created Dillo Hills for the PlayBook, Android, and other mobile platforms. Justin has some great insights to offer on creating games for these platforms!]
PREFACE
Over the past few days, I’ve been working very closely with Adam Schroeder from FGL to playtest Dillo Hills on the Playbook. He’s been very helpful in the testing process, and he’s asked me if I’d be interested in writing about my experience developing the game: from the basic experience of working in AIR, down to some of the specific tricks I’ve used to optimize rendering for mobile.
PROJECT OVERVIEW AND STATS
Dillo Hills was my first experience programming for mobile devices. I worked with an artist (changko) and an audio guy (strike911), both of whom were also new to mobile development.
The game was originally developed for the Android platform, but the code for the Playbook version is almost completely identical, so all of the tips and tricks I talk about here should apply to both platforms!
The game, for anyone who is unfamiliar, is essentially a spinoff of Tiny Wings. Your main goal is to build up speed by rolling down hills, then use that momentum to ramp up into the sky and soar. We built on to the original concept by adding in obstacles, bonuses, and by tweaking the physics a bit to give something that feels a bit more fast-paced and visceral than the original game.
The game was released on Android near the end of March, was approved for the BlackBerry Playbook a couple days ago, and will be coming to Flash and iPhone in April (hopefully). The entire development of the game, from the moment I got the idea to the moment we released on the market, took exactly 3 weeks.
Reception has been mixed, but mostly positive (4/5 on Android Marketplace). The biggest source of negative reviews has been from users who are simply not able to run the game at an acceptable framerate, or experience problems installing the game. Out of all the users who are able to install and run the game smoothly, feedback has been reassuringly positive.
Sales have been pretty nice. Nothing outrageous yet, but certainly worth the time we invested, and still growing steadily. During the first 10 days after the game was released, we sold roughly 3000 premium versions of the game, and had about 25,000 downloads of the free version, which yielded just under 300,000 ad impressions using AdMob.
As for my own impressions of the game? I’m very excited and pleased with where the game is headed, but I’m also very eager to continue working on the game, improving performance, and adding some more gameplay features to keep people entertained longer. I’ve learned a lot of important lessons that will probably have an impact on how I develop games for mobile in the future.
OPTIMIZING TIPS AND TRICKS
1) GPU vs. CPU
The first hurdle you’ll face when developing a game for mobile is deciding whether to use GPU rendering or CPU rendering. Based on my experience, it seems like GPU rendering is faster when you are working primarily with bitmaps (or objects that have cacheAsBitmap=true) and placing them directly onto the stage / display list, and CPU rendering is typically faster when rendering vector shapes or using blitting as your primary means of rendering. Again, this is only based on the testing I’ve done, and your own results may vary. I recommend trying both until you find the one that works best for your game on the most devices.
For Android applications, you can choose either CPU or GPU rendering from the Publish Settings menu (in the Flash Pro IDE). For the Playbook, I had to manually add this line inside the <content> object (which is inside the <initialWindow> object) of my DilloHills-App.xml file:
<renderMode>gpu</renderMode>
However, when I enabled GPU rendering before compiling to a BAR file, the BAR would no longer render anything but a black screen when testing in the Virtual Machine. This appears to be a bug with the VM, as the game runs fine on the actual device. It’s also worth mentioning that Eric Heimburg from FGL was able to get his games to run inside the Virtual Machine with GPU rendering enabled, and it actually showed a pretty significant performance increase even within the VM, so be sure to try it out for yourself!
Dillo Hills was written and optimized for GPU rendering, so most of the techniques I mention here will be directed towards GPU rendering. A lot of these techniques are also great things that you should be doing in all of your applications (especially object pooling!), but are going to be nearly mandatory when developing for mobile.
2) Size does matter
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Read more: FlashGameLicense Blog: Dillo Hills: Optimizing Games for Playbook and Mobile
This tutorial is a previously unreleased recipe from Flash iOS Apps Cookbook and supplements the content found in Chapter 7, Working with Text and the Virtual Keyboard.
