Sparta does look very promising, or at least it did, until about recently (IMO). It's two weeks before release and no demo! When we all thought they would actually rev-up on advertising and start some kind of community for the game, all we get is silence. Something doesn't add up with this. With no community or support as possibilities for Sparta, it's beginning to sound quite familiar to Rise and Fall. That last thing the Historical RTS community needs is another game that dies less than a year after it's release.
It would really be a shame if Sparta ended up another RaF. Apart from quite a few historical inaccuracies (no one seems to be able to make an historically accurate game these days anyway) Sparta looked as if it would be loads of fun and fill in where RaF failed. I still think there is hope, but don't hold out too much, you may set yourself up for a disappointment.
As far as scenario designing goes, numerous reviews and interviews have revealed that there are "triggered events" and in-game "cutscenes" which probably means there's an editor. I'm sure we'll find out for sure whent he demo is released, they usually advertise more game features with that.
The fact that (at least to my knowledge) World-Forge is still around and may possibly make a sequel Ancient Wars:X title looks promising. In an interview, lead designer Torsten Hess hoped that feature Ancient Wars games wuld have more agressive public relations depending on the success of Sparta. I just don't see how it can be successful with hardly any advertising in the first place.