For the last couple of weeks I have been playing a free browser game called Ikariam. It is similar to other free browser games, like Travian. If you don't know the type, think Civilization in a slowed-down massively multiplayer version. I started Ikariam in the beta, where it was still absolutely free, but while you can still play it for free now, you can now also speed up your progress by paying money, something I didn't want to do.
In Ikariam you start with a town on a randomly chosen small island. The randomly chosen part is important, because it means you can't really play with your friends. I joined Ikariam because DM Osbon had told me about it, but our two towns turned out to be far away from each other, so although we were on the same server we just exchanged goods once. And military cooperation would have been downright impossible.
Every island has building materials and one of four possible other resources: marble, wine, crystal, and sulfur. Marble is needed for most buildings beyond the basic levels. Wine is needed to keep your population happy. Crystal is used for research and to improve your units. And sulfur is needed to build most units. As initially you only have access to one of those goods, but need all four, there is a lot of trading going on. Later you can build colonies on islands with other resources, and get all the goods you need.
Where Ikariam is more advanced than lets say Travian is that it has not only land units, but also ships. There are transport ships for trading and transporting goods. And there are ships for combat. The biggest army can't attack you if it comes from a different island and doesn't have enough ships to beat your naval defense. There is also research, which you advance by building academies, and you can research military, naval, economic, or scientific research. That gives you access to bonuses and new units.
But after a couple of weeks, Ikariam got boring. I had access to all goods through colonies, had most technologies, had 1 million gold, and just out of boredom built a huge army and attacked some other cities. It turned out that Ikariam isn't well balanced here. All these browser games have some way for smaller cities to store goods in warehouses so they can't be robbed, so that players that have been playing longer can't simply rob newer players blind. But in Ikariam even large cities can still hide all of their goods away. Perversely the best defense in Ikariam is to build no army at all, because then you never lose any soldiers. And with all your goods safely hidden, even the biggest army can't do you any harm. I did several raids on other cities and never pillaged more goods than the cost of the raid was. And given that an army is immensely expensive, having an army with nothing to do isn't much fun.