Spent all day trying to work out a nice way to generate these kinds of puzzles, and I'm fairly certain that the current method works to within a decent standard.

The general gist will be that you need to walk out a path between the two similar coloured blobs, and that links them up.
A typical colour-path sort of thing.

As stated earlier, I've worked hard to get the level generator to come up with the most fiendish levels possible, but it also makes some nice simpler levels that can be used to ease the player in.

Level difficulty will be based on the number of steps the generator took to make the puzzle, (numbers shown in the image.. You should be able to roughly follow the path it took) along with how many colours there are, and also how much space is left in the level un-stepped.
The generator's quite powerful in that respect.

Also, note that once a "Link" is made, the AI player doesn't step back over the top of the tile, so it gets harder the more you get through the level.

Next up.. Making the game to go with it!!