RPG Systems Family Tree?

[aramis erak]

if it is a tree, then there are no two parents, only ever one.

wrong, genealogy uses the term tree, with two parents per child.
Relationship trees for other systems have and do use more than one parent item per child

revised editions are children of their precursor edition, see above

Does that correctly show all influences? Obviously not, but it is a tree.

Then it's a lie. A denial of reality. A willful falsification/misrepresentation. Worse than useless, to actively damaging.
Especially when dealing with ports of a game to another engine.

Such as T20: traveller's handbook... which is a port of the OTU setting as of MegaTraveller and TNE, to the D20 3.0 SRD with huge tweaks, and some mechanics imported from CT (ship building expanded from CT Bk5, trade from CT Bk 2, world building)...
There are chunks of text taken, under license, from CT rulebooks, MT rulebooks, TNE Rulebooks, and T4 rulebooks... but it was a new design team working under license from Marc Miller, not a corporate in-house situation.

And COC d20 is D&D 3.0 and Call Of Cthulu 4th or 5th.

 

[Enevhar Aldarion]

wrong, genealogy uses the term tree, with two parents per child.

Well, genealogy is more like an inverted tree, with the roots growing up from the current generation person, all the way back as far as it will go. So it is one child per two parents and then on back.

 

[Joshua Randall]

It would actually be interesting to draw a network map solely of games published under the d20 OGL and solely based on what they call out in the, what is it, section 15 of the acknowledgements? The part where you list the other games you borrowed from.

Yes, of course this ignores inspirations you took from concepts, but it would be interesting still.

 

[Bae'zel]

Interesting: I always assumed that WFRP 1e was somehow more closely connected to Chaosium's early output. There's a of similarities beyond the use of a d100. Shrug.

 

[aramis erak]

Interesting: I always assumed that WFRP 1e was somehow more closely connected to Chaosium's early output. There's a of similarities beyond the use of a d100. Shrug.

Chaosium's BRP 1e (1981) and magic world (1982) are the parent of Drakkar och Demoner (Dragons & Demons), and many heartbreakers in Sweden (and Denmark and Norway)... and the most recent edition got a new English name: Dragonbane...

 

[mamba]

wrong, genealogy uses the term tree, with two parents per child.

we are talking about graphs, not genealogy, aren’t we?

Then it's a lie. A denial of reality.

it’s a simplification, and probably the only way to not end up with a complete mess

 

[Joshua Randall]

All models are wrong, but some are useful. (usually attributed to statistician George E.P. Box)