I've decided to throw this into the wild since I haven't worked on it in a few months and there are already a few good KenKen clones on the App store.
The solving algorithm is unusably slow on puzzles bigger than 4x4. I was planning on either optimizing like crazy or, if that didn't work, preloading a few thousand puzzles. Solving, or prefrabricating, is necessary because puzzles with multiple solutions aren't that fun.
- Jon