So, what is the secret of this game? What are the design principles that make it such a success? I suspect they are four (or three, depending on how you count):
- Tension. In NetHack, your character will often be in a dangerous situation, a situation that could easily lead to his or her demise. These situations can come into existence pretty suddenly. (My character, having gone further than any of my previous ones, met a "quantum mechanic" this evening. Ought to have been no problem... except that this guy had a wand of monster creation, zapped it half a dozen times, and out-of-the-blue I was surrounded by a horde from which I could not escape... another death.) And, even more importantly, these situations are really dangerous, because if your character dies, he or she dies. There is no going back. Your save game will be destroyed. Really. This makes for a kind of tension that no game with save/restore-options can provide.
- Complexity. There are so many monsters, items, spells, special abilities, special situations, random effects, special levels, possible actions and so on in this game... it is quite overwhelming. This leads to two effects:
- NetHack lends itself to a lot of exploration. It is fun to find out new things.
- NetHack possesses great tactical and even strategic complexity.
- Hiddenness. For lack of a better term. Even if you use, as I certainly do, the internet to look up the monsters and items you encounter, there is still so much that remains hidden. Every new dungeon level is a mystery, because it is generated randomly. But more importantly than that is the identification of objects. Not only is every object either cursed, uncursed or blessed (which you are generally not told and cannot always easily determine), but all potions, wands, spellbooks, scrolls, rings, amulets and other miscellaneous items start out unidentified. You find a "dark potion", or a "swirly potion", but you do not know what it does. Nor can you look it up on the internet, because these description are mapped onto the kinds of potion randomly in each individual game. There are ways to identify stuff, but they are limited -- you will be spending a large portion of the game slowly finding out more and more. (You could just start drinking all potions, but this is not advisable.) And there are other kinds of hiddenness in the game as well: there is for instance no way to look up your innate abilities (which you can lose and acquire in multiple ways), your luck, your standing with your god, whether you can pray again, and so on. (There are ways to determine these things, but they are limited and not always without danger.) Where most RPGs revel in revealing as much as they can and showing you complex character sheets, NetHack loves keeping you always slightly guessing.
- RPG. It's a traditional role playing game, where you get further and further, acquire new items, gain new levels and powers -- everybody knows that this is addictive.