Why don't you take a look at some of the more popular browser games? An example is
Fallen London. That's the splash page, and you can immediately see that it's more inviting than your login page.
Well, this comparison is a bit unfair, so let's pick their
login page. This looks more similar, but there are still some big differences. One of the most notable differences is the amount of friction - for Fallen London, I don't even need to make an account because I can login with Google. Plus I know what other people are saying about it, which makes me more eager to play. My eyes are directed to the one login box, unlike your website where I can't decide where to focus.
You're probably losing players even before they try to make an account.