Caravel Games describes the DROD (Deadly Rooms of Death) series as "dungeon crawls for thinkers," and that's what they are--an oddly compelling combination of puzzle solving and the dungeon experience.
We won't go into too much detail here--for more information, see the listing for DROD: Journey to Rooted Hold.
King Dugan's Dungeon has been around in different forms for years. It is the original game that started many DROD players' careers. Now it has been upgraded it to make full use of the latest DROD engine. King Dugan's Dungeon now has better graphics, new rooms, new secrets, complete voice acting for Beethro and other characters, and is fully integrated into Caravel's online score and progress-tracking system. KDD is roughly the same size as Rooted Hold, with more than 350 rooms, and dozens of hours of gameplay.