Now is probably a terrible time to make this post, because by this time tomorrow I will be too busy to attend to it for quite a while. A month ago I got the email and downloaded the game, but my experience has been extremely consistent - no shortcut, icon, or application that I can click on with the name "Spiral Knights" does anything. The mouse hourglasses for about a second, then nothing happens. No window opens; nothing.
I am running Windows 7 on a laptop. I can give more specific information if its needed. I'm hoping I probably just missed something stupid.
Try and download the client from this link instead.
Also you may want to update your video driver. Head over to your laptop manufacturers website to find the latest driver.
And make sure your Java is up to date as well.
For this and more information on technical issues please see this technical walk through.