You can find this site's code (not config or data) in the GitHub repo. But that's just a bunch of cosmetic changes from upstream, which is probably where you should go.
For game engine related stuff, Freeciv is your target.
You may also help other projects that fuel this and many other sites, like Apache Tomcat, nginx or Debian.
You can still help if all you have is money. Everybody loves your money.
For this site, you can send one time contributions through PayPal. It should be free for most of Europe using EUR. You can find a more or less up to date report of income and expenses below.
On the other hand, this is something temporal and if it disappears before a year it won't be due to money. So unless there's value in having both this site and the community one, your money may be better spent supporting the One True Community Site.
Freeciv may also thank your appreciation
And if you are filthy rich, you may hire developers and artists to do what you can't.