So since I posted last I’ve plugged through to level 18.
Yup the game rolls credits plus you see the castle disintegrate. That’s the black pile of slag to the right.
And then the game continues to play – level 19, 20, 21, 22 and so on. What it does is mix in enemies from other levels. So in level 1 you get ghosts and bats. But I finished the first 18 levels successfully. Time for another game.