Hey there
We use cocos2dx as we were all about Flash and the web until about ten minutes ago.
Apps are crowded, but we think we can build a community around a family of apps... who knows!!
We keep a watching eye on Unity, but for web 2d has been our choice so far, so all our vector art is 2d.
We do a bit of HTML5 - and will keep going with that but we don't see it as the thing to save us all!
we have just started to engage with Windows 8 and we can use Cocos2d for that too....
MiniMonos.com is a Virtual World we built around ideas of sustainability and generosity. We built a community of 1.5m kids, but are finding the online space just too hard these days,
Best wishes
M