I realize this forum is not as active as it used to be, but in the chance anyone is looking for any games related to the themes in Rise of Legends or other different and unique fantasy rts/rpg/mixed-style games that were similarly under-promoted or less known, then I came up with a short list for you:
The Rise of Legends expansion, Rise of Nations 2, God: The Game, and Crucible: Forge of the Emperor aka Ascendantwere all cancelled but some of the team and work from Ascendant transformed into the rpg Kingdoms of Amalur released in 2012, with a mmo Copernicus in uncertain status. You can check out Ascendant concept art and screenshots here, 4 videos on youtube and 5 longer videos on dailymotion. Some of the locations were influenced by Rise of Legends, so perhaps a little bit of Rise of Legends was carried through Ascendant to Amalur?
If you're looking for any fantasy rts games most similar to Rise of Legends, it seems Total Annihilation: Kingdoms and ParaWorld are the two that are most similar. Below is a list of more similar games that have a steampunk, arabian nights and ancient astronauts/mesoamericans theme like Rise of Legends does:
Ancient Astronauts/Ancient Mesoamericans theme - I couldn't find any particular fantasy and sci-fi games, just the historical Theocracy (2000). - A list of various media with an ancient astronaut theme is here on Wikipedia and Tv Tropes.
There have been various creative, imaginative, less popular and forgotten rts and city building games over the years. Here is an incomplete list of various fantasy and scifi rts and city builder games: