- FUDGE, In his 2023 book Monsters, Aliens, and Holes in the Ground, RPG historian Stu Horvath noted, "Most people didn't see it at the time, but FUDGE marks a fundamental change in RPGs. Simultaneously a system of rules and a treatise on game design theory, it questions many of the methods and mechanics that are taken for granted about roleplaying and reshapes those assumptions, paving the way for other games to continue pushing into new forms in the coming decades.
FUDGE: Horvath is way overplaying its direct influence; it's biggest influence is on Fate - and Fate is where the major market influence happens. It combined many of the concepts from FUDGE, and added aspects from some other game's open source, and brought that combo forward to much more influence than either of its parent games had. It was more important for being one of the first games released as an ebook (even if it was in LaTex and .ps formats.)
My list:
D&D Original - Class & Level, Hit Points, D&D magic, merging several genres of Fantasy into the singular "Generic Fantasy" genre by about 1983...
Tunnels and Trolls – Solo Modules, 1975 release, Gonzo Fantasy in the adventures, damage to Attribute. First dice pool roll & total. (at least, for combat.)
KABAL - proof that TSR wasn't suing over derivative mechanics. And that excess detail didn't sell all that well, but could sell well enough to be worth the time. (I'd love to see it in PDF, in case the creators see this)
Traveller - Lifepath based character gen, skill based play, Damage to Attribute
s
RuneQuest - percentile game, skill driven, first "setting first" RPG, use it to advance it
Palladium's
Mechanoid Invasion &
Palladium FRP - Skill Based, class and level character gen. Same core mechanics, MI published first, but PFRP being the parent game. Classes clearly tailored to the settings.
AD&D
GW's
HeroQuest (HQ): and its sequel, Advanced HeroQuest (AHQ). While technically just a battle game, it had continuing characters, scenarios, and was so close to being a full RPG that many unknowingly crossed the line.
WEG
Star Wars D6... it's much more impactful than the older GB and GBI designs, from which it is derived. In addition to a bunch of other WEG d6 system games (MiB, Hercules and Xena, Indiana Jones¹, Batman, DC Universe), it was the in-big-box-store shelves d6 dice pool, using roll and total mode.
WEG
Batman RPG: the count successes mechanic Dice Pool using custom dice.... in 1989.
Drakkar och Demoner (DoD): first major Swedish RPG - it is (quite literally) Chaosium BRP1e+Magic World with a couple formula tweaks, and BRP 1.0 was a simplification of RQ 1e/2e.
Das Schwarze Auge (DSA): The majorly successful German RPG. To Germans, I've been informed it's more popular than D&D. I've read the English translation... color me unimpressed with the mechanics. But it's popularity in Germany is reason enough to include it, as it also spread to other Germanic language nations. Some having a three way race between DSA,
FATE: the hybrid of Fudge and some other game... brought Aspects to the masses.
Fighting Fantasy: first paragraph solo with rules of play in every module. Later also becomes a standalone game.
Dragon Warriors: First RPG published in mass market paperback format. First to use Roll to hit, roll to penetrate, do fixed HP if both true.
GDW's
Space 1889: used both major d6 dicepool mechanics (roll and total, roll then count successes) in one design... first major invention system. low but long sales, plenty of supplements, died due to GDW having issues with other lines, and having pretty much filled all the non-adventure territory to a decent degree. Alt History, Steampunk.
GW's
Warhammer FRP: first major RPG to be converted from a Minis Battle Game... but I'll note that WFB1 labels itself as both a miniatures wargame and a role-playing game. The entire 3rd volume is dedicated to characters and advancement thereof.
Shadowrun: d6 dice pool with exploding dice (IIRC, it's the first to do exploding dice; it's definitely the first I'd seen.)
Ars Magica: Troupe Style Play (rotating GMing in same setting as the assumed default), Alt history.
Vampire: The Masquerade - first game to popularize a d10 dice pool and playing monsters.
D&D 3rd Ed:
Apocalypse World: first of the story focused games to firmly back that idea up with mechanics. GM is NOT actively plotting... if playing as intended. The GM is making certain things don't stall.
Fiasco scene resolution, single session play as the goal. Not the first such, but the most successful.
I'll note that Palladium FRP either inspired or was paralleled by Bard Games'
The Arcanum, as the two designs differences from AD&D are both: More and different attributes; percentile skills gained by class, advancing at fixed rate, reduced hit point gains by level, high-success rolled to hit, high success rate active defense, armor reducing damage rather than hit chances; many forms of magic with shorter lists, lots of setting elements in the mechanics and in the art accompanying, classes tailored to the setting, multiple non–Tolkienian "races"... (The Arcanum was the rules volume of
The Atlantean Trilogy.) Palladium sets the to hit at 5+, Bard Games to 10+ (but Talislanta later drops to 5+) and defenses the same... but if you've played one, the other will feel much the same.
Palladium FRP is most notable for being a popular entry point into RPGing... it's rarely said, but by comparison to TSR's AD&D 1e, Palladium Fantasy was much easier to grasp, and had an explicit setting in core. Rifts is now the major draw, but Rifts is mechanically just PFRP plus megadamage and more classes.
Star Wars (WEG d6) was first RPG for quite a few, too. Largely because it not only got in game stores, but big box book retail.
VTM was notable popular as a first RPG for females in the 90's. It also had a much larger LGBTQ ratio than many more traditional games.
I've read that many in the UK came in via Traveller, T&T, Fighting Fantasy, and Dragon Warriors. Many came in via Warhammer 1e
Many in Sweden came in via DoD, a few via DSA.
Many in Germany and Austria came in via DSA.
RuneQuest is the grandparent of many Swedish and Norwegian games... (quite literally) Chaosium BRP1e+Magic World with a couple formula tweaks, and BRP 1.0 was a simplification of RQ 1e/2e.
¹: it was released in both Masterbook and D6 versions.