Ubuntu are currently promoting the use of buttons on the download pages of software projects which take the user to the projects page on the web version of the ubuntu software center.
So in this case for Warzone2100 this is the page: https://apps.ubuntu.com/cat/applications/warzone2100/ where the user can read reviews from other ubuntu users and then choose to install if they like what they see.
Currently your website only provides source tarballs which some users may find confusing so this should will the user experience for your ubuntu users.
Here is the wiki page for the promotion campaign https://wiki.ubuntu.com/SoftwareCenter/AppPromotion
And here is the html for the button should you choose to use it.
<a href="https://apps.ubuntu.com/cat/application ... 100/"><img src="http://developer.ubuntu.com/wp-content/ ... button.png" title="Download for Ubuntu" alt="Download for Ubuntu button" width="122" height="49" /></a>
