Some things that make an adventure feel “classic” for me:
The dungeon map (“dungeon” here can refer to a stronghold, caves, what-have-you) is very important to the adventure, and to how the GM runs it. Most encounters are static
, i.e., creatures tend to stay in their respective areas (possible defensive measures aside), waiting for the adventurers to come to them. The adventure is more encounter-driven than event-driven.
A clear sense of the dungeon is essential. The infamous Tomb of Horrors
set the tone immediately (“One wrong move and we’re dead, gentlemen!”) as do other beloved classics. Whether the PCs are adventuring aboard a buried spaceship, lost tomb, big city, fey forest, or enemy castle, it’s important the players have a good feel for the place right away. The PCs/players need not know all the secrets or mysteries involved, but the general nature of the dungeon and the mission should quickly become clear. Dungeons with distinctive levels and/or clearly escalating challenges are extra fun.
Traps and secret doors.
These are must-haves.
Memorable set pieces.
Encounters that make you sit up and take notice, as GnomeBoy mentions. The giant grab in White Plume Mountain
. The “terrible golem” in the Maure Castle dungeons. Silussa and Belgos’ lair near the Vault of the Drow. The stirring, shadow-covered form in the Black Cyst beneath the forgotten temple of Tharizdun. The **SPOILER ALERT** reborn king in the barbarian tomb (DCC# 17). These are the encounters players remember for years, and they define “classic” for me.
A light suspension of realism.
Harley and Jen hit the nail on the head here. Any casual student of history knows that the medieval-type world we envision when playing—long lifespans, sanitary conditions (a sewer beneath every city!), the mix of weapons from different times and real world places, etc.—doesn’t gibe with reality, but, if it’s kept consistent, we approve. Any caver can tell you that most real world caves are narrow,
but we accept the prolific, spacious caverns of fantasy because it is a minor leap to make. We can live with slight oddities such as ogres keeping sacks of gold (where/how do they spend it?) so long as the basic rules (“ogres are generally evil and dumb”) are followed.
I have no trouble watching Star Trek and believing in that universe, but if Kirk and company suddenly beam down without bothering to step into the transporter, that violates my sense of rules—one doesn’t like to see the law laid down and then picked up again. It might seem odd speaking of realism in a game named after giant, flying, flame-breathing lizards, but some rules are mandatory. Classic adventures aren’t afraid to bend them wisely. The DCC line does an excellent job of mixing that old-school feel with a bit more realism suitable to modern gamers, such as less-crowded dungeons, more realistic ecologies, etc.
An emphasis on action.
Combat and action should not be infrequent. There’s a difference between this and the mindless “hack-n-slash” adventure, it should be noted. Classic-style adventuring involves purpose and thought, yet the players still get into the action quickly. To paraphrase a quote commonly (but wrongly) attributed to Marie Antoinette, “Let them roll dice!”
These are a few things that spring to mind, personal preferences only!