I’m trying to make a web browser version of the game using JavaScript, WebGL and Script#. New client will not require any plugins (like Flash, Java, Silverlight or Unity). It will still be possible to use desktop C# client and play together on same servers.

See HexGL and Trigger Rally Version 2 games to check if you will be able to run MD in web browser.
WebGL works best on Windows Vista, 7 and 8, using Google Chrome or Firefox. To run on Windows XP you have to unlock WebGL. WebGL also works on Linux, Mac and even Android.