In some ways, my conception of the Five Spells universe is a special case of the more general Tippyverse. I’m planning on making my 5 Spells book System Neutral, or possibly tack on Savage Worlds, FATE, or some other generalized roleplaying system that are built to be adaptable, but there’s nothing that says that it couldn’t be part of a more “Rules as Physics” universe based on the D&D 3.5 rules, assuming that magic is actually limited to the five spells.
The thing about the Tippyverse that I was most amazed and entranced by when I first encountered the idea was how drastically these changes would affect society. The elimination of the farmer and laborer social classes for example, or the use of Teleportation Circles which effectively introduces Airports and Interstates (but even more efficient) to a world 700 years too “early”. If Resurrection, Restoration, and Cure Wounds exist, how do Monarchs ever die? If Charm Person exists, what does that mean for the concept of free will.
While any one of these questions can be explored in a D&D game, and some campaign settings have tried to answer them more in depth than others (Eberron, and to a lesser extent Forgotten Realms), I don’t think any author has ever done a very good job of examining those questions. Ultimately, D&D is escapist fantasy, and nobody wants to think too critically about their wish fulfilment fantasy reality. Nobody, except, I guess me.
The thing about the 5 Spells idea though, is that instead of trying to grapple with all 360 some spells in the PHB, Not to even count the tons of homebrewed, expanded, and converted from previous editions spells floating around, I’m going to be concentrating on a small number of spells (5 at a time) and examinging how just those spells manage to disrupt society.