"Old school" role-playing games refers to a kind of Golden Age of role-playing game design, before rather significant changes in game design, publishing, and the fan demographic. Old school refers to an epoch of role-playing, but can also refer to retro designs that harken back to that era.
Old School Epoch
Old school RPGs begin with Dungeons & Dragons, the first commercially successful role-playing game. With strong aspects of both gamming and hobbies driving appeal, RPGs of this era also benifited from technological advances such as Xerox and popular interest in fantasy and speculative works. An example RPG of that era is Fantasy Wargaming (1981), a role-playing game that uses the term Fantasy wargaming instead of role-playing game. This era effectively wraps up with the publication of Vampire: The Masquerade and the purchase of TSR by Wizards of the Coast.
Old School Design
While it is difficult to generalize about all the RPGs published in the early days of gaming, some observations can be made about the design elements that distinguish those games from more recent and distinctively current designs.
Old school RPGs, owing to their roots in wargaming, were faithfully simulationistic. AD&D concerned itself with the strategic and tactical aspects of dungeon raiding and quests, Ars Magica with the adventures and researches of magicians, and Toon with the antics of Looney Tunes style cartoon characters. Attention to genre reigned, although games varied in their complexity and zeal for detail. As with many RPGs today, these games commonly focused on combat, exploration, and puzzles.
Strong central narrative
Moreso than in modern designs, old school games tended to assume a certain default format. For instance, D&D assumed you were brave adventurers seeking glory, magic, and wealth. Ghostbusters portrayed the activities of a Ghostbusters franchise, hunting and trapping spooks. Chill assumed you were recruits of a secret organization opposed to a supernatural invasion.
GURPS was an early game to dispense with this assumption, often suggesting myriad adventure possibilities besides the presumed default. For instance, PCs in GURPS Fantasy might be knights of Caithness, but they could just as easily be wizards' apprentices in Megalos or a group of Boy Scouts hurled into the magical world by the Banestorm.
Garage production values
Whether well-designed or true clunkers, old school games tended to be labors of love crafted by hobbyists. Art was often self-supplied or produced by friends. Layout sometimes consisted of simply arranging typed pages in order. Gradually, pamphlets gave way to books, which gave way to the deluxe boxed set, the pinnacle of old school production values.
A small publisher in the modern era may do without fancy graphics, but faces raised expectations in production values. Mid-tier and industry leading publishers operate much like any specialized book press.
Lack of conventional wisdom
Most old school RPGs tend to be either slavish imitations of successful designs, or truly unique creations. With few guideposts and an undefined target demographic, creators often verved away from supposedly common sense design philosophies. The results ranged from sheer folly to pure genius.
- Boot Hill was part miniatures game, part RPG, and had little in the way of traits besides combat statistics.
- Villains and Vigilantes suggested you play yourself as a super-hero
- Marvel Super Heroes generally assumed you would play existing Marvel characters, but otherwise encouraged you to simply make up appropriate characteristics for your own unique heroes or roll randomly
- DC Heroes also assumed you play published heroes, but included rules for point-based character creation that would eventually become a main selling point of the game.
- Paranoia had you play a clone with six lives.
- In Ars Magica, you played a magician who spent as much time copying spells, researching, and politicking as going on adventures, fighters were treated as lackeys and communal property, players had more than one character in play and downtime was an important play element.
- In Teenagers From Outer Space you simply could not die, and had to worry about succeeding too well at tasks.
- Vampire: The Masquerade cast players as vampires, traditionally a monster adversary, and emphasized narrative structure over rolls or game mechanics, making it practically the last old school game and the first new school game.