Andrew Plotkin's new game The Dreamhold is out. The Dreamhold is aimed at beginners, but many of its beginner-oriented features can be turned off if you want a more challenging game.
Of course, you can turn off the hints and the tutorials, and play
The Dreamhold as a real game. The puzzles are not extremely
difficult, but they should offer some challenge to both experienced
players and newcomers. (If the challenge is insufficient, there's
an "expert" mode which makes some of the puzzles harder.) There are
also many optional bits to explore beyond the main storyline.