A LOT OF WORK!!!
But seriously its just like any other Isometrics game, just the game play structures is set out differently. User structs a lots to keep up with your data. Also good books to check out are any dealing with Isometrics and/or RTS Real Time Stimulations/Strategy. Also instead of combat focus more on city building. Same for your backgrounds, and just blit a tile to a place on the map for your buildings units etc...
