Big Huge Games today announced Rise of Legends, a "spiritual successor to Rise of Nations" but set in a steampunk world. Though no longer a history game, Rise of Legends will still feature Rise of Nations game elements like national borders, color-coded tech tracks, and cities. Some screenshots can be found here. Here's what Big Huge Games president Brian Reynolds had to say about the game

Rise of Legends is in so many ways the spiritual successor to Rise of Nations, but the long and the short of it is we got excited about doing a fantasy game. Now clearly your traditional "orcs, elves, dwarves" sort of fantasy has been--shall we say--thoroughly covered in other games, and so the story which got us excited is one where the magic of fantasy meets a world of technology. So magic and technology collide, with cataclysmic results! As you take a peek at our first two unique nations you can begin to see the contrast: the industrial Vinci with their Leonardo da Vinci inspired machines and steampunk cities; and the desert Alim with their Arabian Nights theme--sandstorms, genies, and tall glass spires. "Cataclysmic" is also a useful word to describe what we want to do visually