CSG

I have been told that I have been playing this game for 3 years now. I suspect its longer.

The beauty of this game is that if you want, you can login once a month. I have a faction mate who did that till recently.
Or you can be seriously super active.

There are various things you can do. Play it as an economy game, or a war game. My team have generally played it peacefully. Recently, we play it as war. The fun is finding and killing the enemy without being killed.

A full review of this game would take a lot of writing. It becomes extremely complex.
Yet for the newb, who starts off the economy game, its extremely simple.