Well, not true RPGs in the same sense as most. They are actually Strategy RPGs/wargames with a sort of Civilization mix to them, so you might not automatically stick them into the RPG genre, although most PS2 sites do. They do have quite a lot of RPG elements in the mix though.

Having just completed section R of the site you probably noticed the first two games in the series were released on the Amiga We have them listed as Wargames which they could also fit under.

update: I also downloaded RTK XI but like you I only quickly ran it to check it worked. I've just read a review and it seems KOEI have butchered this latest version and removed all the fun stuff, leaving mainly just a large scale wargame. They have upgraded the graphics to a full 3D engine but cut out all of the sub ruler stuff.

In RTK X you had the ability to not just concentrate on being the ruler. You also have the ability to choose to take control of any of your officers in the food chain and explore your kingdom with them. Focus on developing each character as you play them, building skill and reputation, travel the country performing tasks for the locals and being able to sabotage and recruit under the local ruler's nose. All of this is the RPG element I was talking about, and it seems they have removed all of this from the latest XI game which is very sad news. For this reason fans are saying everyone should stick to RTK X as it contains all of these great features.

It also seems they removed many other features from the latest version too, including detailed alliance control with bordering regions. Before you could call on your allies for help in a battle, but now it just gives you the ability to move freely in their regions without your own forces being attacked, and no control or aid features from the old games exist.

So basically, if you want to play one of the RTK games and really enjoy it and get the most out of it including all the fun officer RPG bits stick to RTK X and don't touch the newer XI.