Unity great strengths are the easiness to go from concept to implementation and its support for deployment in multiple platforms. It's not that easy, I can tell, after finishing a project with iOS and Android support but once you get it right, it works.
You can play it online if you have the Unity plugin installed.
The source is in my repository.
Right now this port is missing the HUD (and for a demo this size stock Unity GUI support would be somehow OK) but I better don't bother because the GUI system is one of the Unity weakest points and it really sucks big time. Due to performance issues is plainly unusable for mobile devices and it's pretty archaic and limited for everything else. You'll need to buy expensive third party plugins or use (and probably modify) the nice and free UIToolkit for sane and usable interfaces in your games, but even then you still will miss support for advanced containers and scrolling. Sight. The good news is that Unity 3.5 will have a brand new GUI system. I really really hope they fix it for then.
So please forgive my laziness but my fingers chucked and rebelled against me when I was trying to type OnGUI(), and using old fashioned GUIText is not my thing :D
Forgetting the GUI, Unity is an awesome and very fun engine to play with, and it's FREE.
Programming in C# with Visual Studio C# is also a pleasure.