Yup cocos2d, with a pretty thick custom level editor built on top.
is the level editor your own or another product?
I built it myself. It is in the form of a Fireworks extension. I lay out the levels inside of Fireworks and export both the art and the level as a package.
I will open source it eventually.
I am very interested in taking a look at your level builder.. i am even willing you pay for it :)
Also, are you available for freelance work? contact me at ob.ahmed[@]gmail[.]com
Please post when you do, I'm just getting into cocos2d now trying to learn game development. Any tips/resources you can share? I'm working through this book http://www.learn-cocos2d.com/
I was an early contributor to Cocos2d, Riq was always looking for a good level editor and produced his own eventually (http://www.sapusmedia.com/levelsvg/) but it was a bit limited. I'm sure he'd be interested in your work, have you reached out to him?
Knowing nothing about Fireworks, in what language did write the plugin?