Attack rolls vs AC
Hit points
Saving throws
Vancian magic
Class levels and XP
Wizards, fighters, clerics, rogues
Paladins, druids and rangers (not necessary as a class)
Humans, Dwarves, Elves, Halflings
Medieval weapons and armors
Dungeons
Traps
Turn Undead
Orcs, Ogres, Trolls, Giants, Undead, Dragons, Werewolves, Mind Flayers, Beholders
Fireball, Invisibility, Fly, Scrying, Teleport, Polymorph, Wish (and others)
Daily-based resource management, including the need to rest after a few encounters
Possibility to play with just pen and paper (no map or minis)
...and a certain feeling of wonder!
