Tower Defense HTML 5 Game

I am looking for Proof of Concept game to be developed from the ground up. This means the basic engine and media elements (art, sound effects, and music) all need to be included in the quote. The game is your typical isometric tower defense game with a twist - it also allows a reverse game mode (where the player is the attacker on a fixed base). The game needs to run on Microsoft technologies and use VS2010/VB.NET on the backend. HTML5 is the preferred rendering engine so it can run in a browser and on a tablet. Other smaller mobile devices are a future possibility, but this POC needs to at least run in a browser and on an Android tablet.