Try the Viking History game over at BBC. It is a great idea to use games like this (this one using Flash) to teach history. I learn some things about viking ship building and the routes ships took to the British Isles.
However, the point of the game seemed to be to kill lots of monks and collect as much treasure as possible. I guess that is realistic enough (though I wish it accounted for the trading and settlement aspects of the vikings, perhaps if you successfully complete the first mission)…but leaves a bad taste in the mouth for a game of educational value…
The concept, however, I think is great and can be applied to all sorts of things for children learning history. I remember I learnt a lot of my geography from games like Where in the World is Carmen San Diego etc.
I would like to play it!!!