Not really. It is fantasy, not non-causality. Like I said, it is the difference between "what if...?" and "whatever...." One can posit an alternate reality where magical forces exist but still have them operate in relatively predictable ways, or at least within "rigidly defined areas of doubt and uncertainty." Characters do not cast fireballs "out of nowhere," but out of the mystical arcane forces understood as normal and natural to the game world, and only after years of meticulous study. AD&D never let rookie mages cast fireballs, as much because it would be unrealistic as because it would be game-breaking. It also never let characters cast infinitely large fireballs dealing infinite damage, because there is a limit to how much even AD&D empowers munchkins playing would-be deities.


I do not think GURPS that inaccessible to new players, with the notable exception of the GM. Someone who has never roleplayed before can be integrated into a GURPS campaign fairly quickly as a player, but the complexity of RUNNING the game all but demands a veteran GM. Players do not need to know all, or even most, of any systems rules, but GMs do. Again, Instant Characters is all of four pages long, and half of that is just a list of all the dis/advantages and skills available (it really should have included a minimal equipment list though, because you cannot complete that last step of character creation without the main book.)

As to adventures, SJG has begun offering more adventures in recent years, and many worldbooks contained sample adventures. The original Basic Set had two; the All in a Nights Work solo adventure that required no GM, and the Caravan to Ein Arris module for a full party. The former even listed the alterations necessary to convert the generic medieval setting to a post-apocalyptic one (Max the Guard instantly becomes a lot more lethal carrying a shotgun rather than a scimitar.)

However, GURPS did not make a habit of printing modules, because it did not want to paint itself or its players into a corner. It was created at a time when many experienced DMs had already exhausted all the TSR modules on the market and were forced to either invent their own or stop gaming. GURPS gave them a comprehensive way to do that for any conceivable setting(s,) and pigeonholing them by restricting them to ONLY Yrrth or some other game world would have been counterproductive.

The thing is, you only have to master GURPS rules ONCE, and then you can create any adventure from scratch, from a minimalist non-magical Stone Age campaign to a high magic AND science Spelljammer/Star Wars mashup. The main difference between GURPS and most other systems is accommodating all that diversity without the need for a whole new set of rules, and without becoming so absurdly unrealistic and/or arbitrary your players bite their tongues to avoid falling over laughing at every single event in the campaign.