Like I've said before, you need to install Unity.
https://unity3d.com/webplayer
Both Firefox and Chrome have said that, like Flash, Unity is a security concern. Java, Flash (Adobe products in general) and Unity have been dropped from the browsers. Chrome and Unity can work, but Unity needs to be installed to your computer.
Certain IE browsers do not support Unity (it's not they can't support it - it just won't run). You can try Edge if you have Windows 10.
Edit: You'll see a message that Chrome doesn't support Unity, so I'm assuming that the way it runs within Chrome is that Nutaku is running a server extension of the web player, however I haven't noticed any connection issues as I have Unity already installed on my computer for other browser games that required it, and it ran separately from Chrome (but still within a Chrome framework) A game like Akatsuki no Kiseki (英雄伝説 暁の軌跡) requires it.