Cocos2D and Spritebuilder
Apportable a San Francisco-based start-up later acquired by Google, paid Scott and me to develop the Cocos2D-ObjC game engine.
While at Apportable, I helped port several games (three or four) from iOS to Android using Cocos2D, and their reimplementation of CoreFoundation for Android. I then helped out with the Chipmunk Physics integration, the SpriteBuilder editor, and various engine features including: Tilemap improvements, performance testing, texture loading, Wwise audio engine integration, scheduling and race conditions fixes, and lots of code documentation.
I was the 10th most active contributor to Cocos2d-objc.
The demo above is Galactic Guardian . Scott put together some nice design notes about it. Victor wrote a bit about the effects and 2D lighting of Galactic Guardian .