Dominus is an online strategy game where you have to take other peoples' castles while defending your own and getting resources. It is mainly free but the pro account doesn't really do much more so it doesn't really make a difference. The game has different speeds of game and I prefer the relaxed games because it happens quite slowly and means you don't have to be looking at it all of the time. Some of the mechanics in the game are quite complicated and hard to understand but it has a very good help option so you can easily understand (this resolves the fact that it doesn't have a tutorial). The goal of the game is to be a lord of everyone in the whole server. To be a Lord of someone you have to take their castle. As a reward for taking a castle you will get 10% of your vassal's (person who you are a lord to) income. The game is not optimised for the phone but it is possible to play it, although I wouldn't recommend it.
I think it is a good game and I recommend you play it!
dominusgame.net
