[zorked]

Nethack runs as a setgid process that hides save files from users.

Kind of old fashioned now that almost every Unix system is a single user system. There are still public servers for those that want the temptation to be taken away from them.

As to spoilers... Everybody reads the spoilers. I doubt anyone has ever ascended spoiler-free.

[Steuard]

[Possible obscure spoiler]

A friend once showed me a post on rec.games.roguelike.nethack where someone was finally begging for a hint because they'd gone deep in the dungeon and couldn't figure out anything to do next. They couldn't find any staircases down, though they had found a weird vibrating square, and none of the many weird items they'd collected seemed to do anything to help.

[why_at]

This is one of the things that makes a spoiler free run hard to imagine. I think the Oracle can tell you about the ritual but geez it would take you forever to figure this stuff out

[chongli]

There is a story of a purported very deep spoiler-free run [1]. The person made a journal of everything the Oracle had to say (over multiple games) and was able to figure out a lot on their own as well.

[1] http://nethack.gridbug.de/ellora/TheElloraSaga.pdf

[ForOldHack]

The ! command. If you run as SUID anything, and the UNIX you had, had a SUID bug, then the shell command SUID as root. Scary when you were running on a "secure" version of UNIX, and it had a SUID bug.

On DOS, the ! Command, gave you access to the levels files, for which you could make a closet level.

I always started a few rounds as every role, and watched the hilarity begin with the stupid ways to kill yourself, which after a few months, were always hillariously fun to read.