Is there a framework for pnp RPGs that allows you to compare the game mechanics between different editions of a game?

[GuardianLurker]

Now those could be meaningful for multiple game systems.

That would add:
Turn Order/Initiative: Individual/Group/Hybrid; Randomized/Adjusted Order/Fixed Order; Periodic Resets/Purely Cyclical

• 1e and 2e have initiative that is Individual, randomized, with frequent (every turn) resets.
• 3e and later have initiative that is Individual, Randomized, and Cyclical. Though the GMs in all editions tend to change the Individual to Group, purely for practical reasons.
• FFGs Genesys games have a Hybrid/Randomized/Reset initiative. The character roll initiative every turn for party use, and any character can use any roll (once).

Skill "Scale"/"Use"/"Granularity" (no good term comes to mind): Character-based (e.g. Backgrounds as Skills); Broad/Generalized Skills (e.g. D&D 3e, many others); Narrow/Specific
Skills (e.g. GURPS); Skill Trees (broad-to-narrow-to-specialized). Additional variant: Weighted cost by player/system/unweighted.

• 1e and 5e both have Backgrounds-as-Skills, with no weight attached.
• 3e and 4e are both broad skills, with a system specified (and limited) weight attached.
• 2e is a broad skill, with no weight attached. (Ditto for late 1e with the Survival Guides.)
• As a further example, Rolemaster has skills that are specific, arranged in a limited skill tree, with a system-specified weight.

The AC changes are already covered as "roll vs Target" and "increased consistency across the editions", in my opinion.

There might also be a reasonable cross-system "Combat Lethality" term. Super-heroic/Heroic/Death Spiral/Lethal. I'm less sure about the gradations on this, or even if this makes a meanigful difference.

Spoiler: A side discussion

And not to denigrate Deset Gled and GMMichael's points, but categorizing game MECHANICS is a very different thing from categorizing Game Design or Game (Design) Theory. Those are both much more nebulous concepts. Even just the "Rules-Light" vs. "Rules-heavy" debate is evidence of that.

Strangely enough, if you avoid trying to define the terms explicitly, or nail down commonalities in design and philosophy, I think you'd find that most people could sort game systems by "rules-weight". At least, each game relative to each other game. I'll also admit that even that situation would be more inexact than my rough statement implies. There's a lot of "I can't define it, but I know it when I see it" going on here.

 

[aramis erak]

some elements to add to Guardian Lurker's list of things to ID:

Rules approach:

• One single mechanic used for all mechanical occasions. (Includes most PBTA and MegaTraveller)
• Two closely related mechanics (Houses of the Blooded: combat is a variation of the normal resolution, but adds an extrapolation for initiative and actions - the "initiative Risk" is a relatively normal risk roll, but your wagers are how many turns you get in the round, and your initiative is how you rolled on the dice.)
• Two different mechanics to cover all mechanical occasions (Starships and Spacemen {anything but melee, melee},
• Three different mechanics (Palladium Robotech {combat rolls, Saves, skills}, Tunnels and Trolls {combat, saving rolls for non-combat or resistance, casting rules for magic})
• Multiple different mechanics: AD&D (combat, saves, racial abilities, thief skills, Psionics), Classic Traveller (unified combat, but most skills include a unique subsystems; many ignore the special cases and just use the combat roll for non-combat skills.) Palladium Fantasy (Combat Rolls, skill rolls, saves, casting)

Rules Consistency

• No changes from main mechanic(s)
• main mechanics include several exceptions, but all the various special abilities are just applying that handful or two. (2d20 Star Trek Adventures, 2d20 Dune)
• Some abilities are exceptions to main mechanics, but remain close
• Many abilities are exceptions/additions to main mechanics, also calls "rules-by-exception" - D&D 5 goes there with Feats and Class Abilities - both of which are exceptions to the unified resolution mechanic.