I don't have a lot of isometric-specific features planned. It depends on how far the current design will get you. One of the biggest hurdles to isometric game development in GameDev 1.x was the fact that you couldn't properly interleave the sprites into the tiles, nor could you properly define solidity at angles that weren't multiples of 45 degrees. Now that SGDK2 supports that, I think that's a big step in the right direction and I guess my first inclination is just to release with that improvement and see how far that gets us. I'm not planning to support 3-D maps or anything (I'm not going to intrinsically support staircases to other levels/layers of an isometric map) but I wouldn't be surprised if that turns out to be trivial given the new features that are already available. So far all I'm planning to support for isometric maps is what I've already done: allow sprites to draw between rows of tiles (based on Y coordinate), and allow tiles from each row to overlap tiles in rows above (allow tile graphics to be bigger than the tile). Oh, and allow solidity to be defined by arbitrary formulas (I haven't fully implemented solidity reactions yet, but you can define solidity based on arbitrary formulas).
