AS3, PHP, MySQL, JavaScript and Facebook Connect.
This project was born of testing verlet physics, something I started getting into since flash on the beach 08 and have used in a lot of projects since. Verlet integration is quite straightforward and I suggest taking a look at this great article at Gamastura Here if you are interested in learning more, it has everything you need to get started.
Another rather nice feature of this project was the water effect, this was created using particles and bitmap manipulation. The particles are drawn to bitmapdata and then a threshold filter is applied, this is then blured and the visual effects are applied. The end result is what you see in the game, a nice looking water effect.