Turn-based strategy warfare is a genre that's surprisingly easy to come by on iOS -- there are a lot of games out there that let you pit various forces against each other in a turn-based battle. But it is hard to come by a really great example of one of these on the App Store, and fortunately Ravenmark: Scourge of Estellion does it right.
This is the first game from a company called Witching Hour Studios, and as their website says, the title shows that they're trying "not so much to make a quick buck," but to actually set up a story and a world that feels epic even on the iPhone's little screen.
Ravenmark feels exactly that.
The story and lore feel super solid, and the tactical gameplay uses a sort of expanded rock/paper/scissors system that plays well and offers up all sorts of engagements to command. Various troop types do more damage to others (ranged defeats infantry, for example, but ranged can be beaten by cavalry), and troops can be joined up into sets of one, two, or three, each with their own abilities and special functions.
If you've never played a turn-based strategy game, this one might get you into it. It's relatively simple, though obviously can get more complex over time (and there's plenty of depth here to explore over 15 missions, if you do want to get into the nitty gritty of tactics). The graphics are clean and smart, and while the interface does kind of boil down to a series of menus, it's still simple enough that it's easy to direct your troops to where they need to go. There's no RPG elements, really, other than an really deep ongoing story, but this game doesn't profess to be an RPG, so it works just fine (for now -- it definitely feels like there are more games to be set in this world).
In fact, the only issue with Ravenmark is that it is so short, and it's constrained only to the small screen for now. But both of those issues are set to be fixed with a free update by Christmas (with new content and a universal version), so if you're interested in either dipping your toe into turn-based tactical strategy, or just really want to play a very well-done and polished example of the genre, this one's for you. It's available right now for US$2.99.