So here is Simon’s Cat in Cat Chat, an iPhone game for Simon’s Cat.

It was a lot of fun to build. Lots of work, but that’s because we are perfectionists, and Simon’s Cat is such a beautiful piece of animation that we felt we owed it to the cat to put the extra hours in.

First up, thanks to the iOS widows, Nancy and Diane, and the kids who put up with dads constantly asking them to beta test the app for the past couple of months.

We’d also like to say a huge thankyou to the guys at Simon’s Cat – especially Mike Cook, Simon Tofield and Mike Bell – for making this such a fun project to do and for being so positive and easy to work with since the inception of the game idea early in 2011.

Steve would like to say a very big thankyou to the fantastic Ray Wenderlich whose tutorials on iPhone coding, and whose book Learning Cocos2D…, written with Rod Strougo, was a brilliant and clear introduction to Cocos2D back when we were just kicking the idea of building an iOS game around. Can’t recommend it enough if you think iPhone games is what you’d like to do.

“Simon’s Cat in Cat Chat” was built using the Cocos2D framework for iPhone. Riq and the Cocos2D community have been an amazing source of information, inspiration and help – and the framework rocks for building iPhone games.

We also used the formidable Box2D physics library to render all the physics. This is a lovely library developed by Erin Catto, and is definitely the tool of choice, we think, because of the community support and forums that surround it.

Along the way, we also found some other lovely tools. The guys at 71squared deserve a mention because of their two great products Particle Designer and Glyph Designer, without which building the fonts and emitter in the game would have been less than fun.

Another cool one was VertexHelper, which, although not quite there as a release-quality app, made it just that much easier to translate PNG graphics into Box2D shapes. Massive thanks to Johannes Fahrenkrug for putting that one into the open source domain via GitHub.

Lee used Zwoptex to build the game spritesheets, which were generated from Simon Tofield’s original animations and new drawings done by Lee in Adobe Flash. For the record, Flash still kicks ass, despite what Apple may say about it.

Other software used in the creation of the game includes Logic Studio and Soundtrack Pro 3 for sound effects (bouncing an apple off Lee’s head sounded good with a bit of compression), Xcode and Adobe Fireworks – a hugely underestimated piece of magic for translating vector graphics to bitmaps for use in iPhone games and the wider web.

We also used Paper, a phenomenal tool when it comes to sketching out ideas in a form that allows discussion and development.

The things we learned…

OK – here’s the big one: if you are using spritesheets in your game and want to support older devices like the iPod Touch 2nd generation and the iPhone 3G, YOU CANNOT LOAD A SINGLE SPRITESHEET BIGGER THAN 1024×1024 PIXELS.

We were delighted when after a few days the app had entered the top 50 on the UK App Store. But what were these 1* reviews? App not working? Won’t go past the menu screen?

It transpired that we had missed one crucial limitation of the older armv6 devices as we worked so hard to run the game on a single 2048×2048 sprite sheet… they couldn’t load it. Easy to look back now and think it should have been a known fact – but its surprisingly quiet, unless you are testing on those old devices. We had made it compatible from an iOS standpoint – it would run all the way back to iOS 3.2 – but the hardware has a part to play too.

So the lesson learned is simple – get old devices and test on them if you plan to support them.