Nothing new...
The engine is great and works nicely but its definetly getting stale by now.
Not only you used the same engine than most of your latest games, but also you recycled the concept and only changed a few things. I'm not saying it's a bad thing regarding you own commercial purposes (which is great by the way to keep milking a little engine for so long), but origonality-wise it's has already reached it's peak and you'll need to make some strong new features to make it feel new or focus a new genre.