Evony is an online strategy game that loosely based on the Middle Ages. You play the role of a Lord overseeing your lands, defending your cities from attack. You also get the chance to attack others to gain resources and wealth, or you can settle in and try to build up your cities. It is kind of a combination of Sim City and World of Warcraft.
Recently, Evony adds have been popping up all over the internet, especially with Google's Adsense program. They also seem to be running a campaign on DoubleClick. Anyway, since I saw the ads, I decided to give the game a whirl. I tried it using both Windows XP, and my Linux PC with generally the same results.
The game starts fine, but then after a while performance begins to suffer. There appears to be a slow memory leak in the Flash media program that Evony uses. Simply refreshing your browser corrects the problem. I have found that you can play a little longer between refreshes using Google's Chrome browser on Windows XP. For Ubuntu, your best bet is to use Epiphany. It is probably because these browsers have a lower memory foot print over the browser bigboys.
The game uses Flash media as part of its engine, so you will need to be certain of have Flash installed on your Linux PC.