I haven't played Nations, and I very much like Historia at 2p+ but I thought it fell really flat solo. Without the tension of any other non-bot player playing the revolution card, it really reduced the decision space (in my opinion).
Historia fell flat for me for the same reason. It's very functional and easy to play, but the most intriguing part of the game is figuring out when to play the revolution card to get the added benefit. In the solo mode, you can play every card in your hand if you want.