You play a turn every 24 hours or so. I’m playing one game right now, and I play a turn every morning when I get into work — it takes about three or four minutes. I’ve developed a decent corner of the map, but I’m pretty sure I’m about to get whalloped by someone.
The nice thing is that there are dozens of new maps to try, which changes the dynamics of the game quite a bit.
It’s free, with premium memberships for those that want private games or to play lots of them at the same time.