У вашего броузера проблема в совместимости с HTML5
My first game i've developed with C# and XNA Game Studio.
Due to time reasons I never really finished it. It was more like a tryout to see what's possible with XNA. Still you can download it from www.thauros-clan.de/thauros-defence.rar if you don't care about the bugs / imbalance.
You'll need to have the XNA Framework installed to run it.
*Update*: I'f you want to look at the source code (only the .cs files), you can find it here:
http://www.christoph-goettert.de/source.zip