Actually, frogatto's got a lot more than just a map editor: it's got a full interpreted "semi-pure functional" language in it called FFL, and all of the game logic is in this language.
It's basically suitable for almost any 2d game built from rectangular tiles and freeform 2d objects (there's a little bit in it, like tile-size, that's hard-coded, but we can fix that in a heartbeat if anyone who needs something different approaches us with a serious shot at a new project - we're probably going to fix those anyways as we make the stuff I mention at the bottom of this post). It's also extremely well-optimized, able to run at a full 50fps even on a gen1 (e.g. 412mhz) iPhone - the engine is based on OpenGL, but has tons of features for pixel-art stuff, like per-pixel collision detection, palette shifting, parallax layers. We've even got some fun stuff like particle systems and positional sound effects that fall off as you get further away from them.
We have already made tech demos of a vertical-scrolling space shooter, pong, and I have a chrono-trigger* style rpg in the works as I speak.
Our documentation still needs work, but it's at least no longer nonexistant; you can check it out here:
http://www.frogatto.com/developer It's going to be a bit confusing at the moment unless you get in touch with us on IRC, because we don't have any really general tutorials yet, just low-level technical stuff, but that will change over time.
Also, we're looking to build a library (probably working with
OpenGameArt.org) of pure public-domain art which will be pre-built-into a "game maker" oriented release of frogatto's engine. This will be some simple (think rpgmaker), blocky art you can use for any number of game types, be it action rpgs, some classic arcade games, top-scrollers, or whatever. But it'll be public domain - you'll be able to enhance it, add to it, and completely use it as though it's yours!
The best part is that our engine is under a dual-license like QT, so if you want, you can license it commercially, rather than having to open-source your stuff as well (which, let's face it, usually forces it to be free-as-in-beer).
*loosely; there's a lot of influence from other stuff, and the tactics are going to take a lot of design lessons from wesnoth to heart. I really want to break the mold with some interesting combat innovation.