If you're a fan of challenging non-DROD-like puzzles, you should definitely rush to check this hold out. Here, the puzzles are presented in an attractive setting, complete with story, and the added challenge of finding and reaching the secret rooms.
For the most part, these puzzles were very well executed. My favorites are:
A hysteresis puzzle:
Under the Mountains : The Underground Path : 1 North, 1 East, where the player moves only on a NE-SW diagonal, but manages to work a mimic north to its goal by sliding it against pits.
A small fractal maze:
Under the Mountains : Eternal Stairway : Entrance, a puzzle type that I hadn't successfully solved before. This one was not too easy, but not too hard either, and it was small enough that I actually figured out a strategy... which was fun.
An aumtlich puzzle:
Under the Mountains : Training Grounds : 1 East. This one is a non-non-DROD-like puzzle, so of course I liked it. It involves clever manipulation of aumtlich from a distance.
However, some of the puzzles included don't work so well with the DROD user-interface. As one example, I had never seen a "
rolling block"
puzzle before, so the alternating negotiator - mimic characters in its DROD implementation,
Under the Mountains : Training Grounds : 1 South, 1 East made no sense to me. I eventually went to
a page on the MathsNet site where I could practice this and other rolling block puzzles in a friendlier interface. Also, solvers of Under the Mountains have the added challenge of a scarcity of checkpoints.