The improved game engine and the new civilization are well worth the price of the Kingdoms expansion pack. It's a very good deal if you liked the original Kingdoms. If you had technical complaints with the original but liked it fairly well otherwise, you should also consider picking up The Iron Plague. But if you liked nothing about Kingdoms, then you still won't enjoy it with The Iron Plague. That's because the essence of the game hasn't changed; resource management remains overly simplified compared with other real-time strategy games, groups of units moving together still seem to act as if they're in a Keystone Cops movie, and battles still frequently turn into exercises of mutual attrition. But the new units, the new maps, and the new campaign add a lot to the original Kingdoms, which can only be a good thing.