Fully Stage3D accelerated, fully Flash. Never heard of Angry Birds? Here is more background.
Angry Birds has been praised for its successful combination of addictive gameplay, comical style, and low price. Its popularity led to versions of Angry Birds being created for personal computers and gaming consoles, a market for merchandise featuring its characters and even long-term plans for a feature film or television series. With a combined 500 million downloads across all platforms and including both regular and special editions, the game has been called “one of the most mainstream games out right now”, “one of the great runaway hits of 2010”, and “the largest mobile app success the world has seen so far” [via Wikipedia]
For more details, read Diana Helander’s official blog post, and play the game on Facebook.