Gelatinous Icosahedron

 Being able to assess the risk of adventure locations is a vitally important aspect of old school play, especially the sandbox style. In dungeons, this is a relatively simple matter: the danger increases as you descend deeper into the dungeon. Dungeon levels are typically numbered, starting with 1 for the first level, typically the most easily accessible, and progression to higher numbers with each level farther from the main entrance. Monsters found on a given level will tend to have the same number of Hit Dice as th e dungeon level (e.g. on the third level of the dungeon, 3 HD monsters are most common) and more loosely, traps and other hazards become more deadly. The amount and value of treasure also tends to increase with dungeon level. There are some twists on this formula; some dungeons may have additional entrances that lead directly to deeper levels, and some dungeons may be "layered" horizontally rather than vertically, but the overall principle is that players will b...

 One of the tropes of D&D, and fantasy RPGs generally, that I've come to dislike the most is the cosmopolitan society depicted in so many settings and adventure modules. It's arguably reached its apotheosis in modern iterations of Dungeons & Dragons and its close kin, in which not only dwarves, elves, and halflings, but orcs, lizardfolk, elemental-kin, half-demons, and even more outlandish beings regularly coexist closely with humans and each other, socializing, working, cohabitating, even interbreeding freely. Even in older products, as well as more recent OSR and OSR-adjacent material, however, the trope is in evidence. Try to think of the last human village or stronghold described in an old TSR or newer OSR product which actually featured a human smith instead of a dwarf. Setting aside that most wildly overused cliche, though, you'll generally find that almost every predominantly human settlement will have enclaves of non-humans, and NPCs prominent enough to warr...