Well, Assassin's Creed has a great storyline along with an addicting gameplay experience and realistic graphics. There are three main installments currently but Ubisoft Montreal has already announced the probable release of a fourth one. It is on almost on all platforms include PSP and Nintendo DS.
Thank you so much for the list. Have been looking for a decent one since I found some free mmorpgs. By the way, you could also include Free Realms, its a cross-platform mmorpg that is free up to an extent. Anyways, thank you again for the list.