Make sure you have installed unity web player plugin
first Disable popup block if it show
If you see "unity webplayer install now" image in browser window then you must install it first.
Restart your browser after plugin install.
Google chrome will display a gray box with the message "Unity Player needs your permission to run". At the same time you will also see on your toolbar a message with two buttons saying "Run this time" and "Always run on this site"Your game will run after selecting any of the message.
In this case you look on your tool-bar where you will find two buttons to activate the plugin either permanently or just for once. If you ignore this, the game will not run.
Source > Unity3diy blog