Pinnacle: It's one of my favorite strategy games. The difficulty is roughly equal to Warcraft 3 on hard.
Plus, there's a spell called Intestinal Vaporization. What more could you want?
Bovine Intervention, that's what you could want ;-)
This is a great game in my opinion, there is nothing else I've ever played quite like it. Most real-time strategy games place you in a position to see the map far removed from the battlefield and the best they do to link you to the action directly is to have hero units or something like that. Sacrifice really puts your character in the thick of the action and gives you a unique perspective on the landscape and your units. You need to deal with the difficulty of not really being able to see beyond your own vantage point. The minimap is there certainly, but you don't really know what is coming unless you get your wizard out there.
The difficulty is initially somewhat harder than typical RTS games but once you explore various combinations of spells, creatures and tactics, you'll get into the swing of things. Just make sure you recover your own souls and do your best to steal them from your opponents!
Anyway, if you're looking for something new and different, Sacrifice is a great option despite its age :-)