Biggest potentials in media that will never FULLY materialize, just leave people yearning for more?

Not "biggest waste of potential" as in "good idea, bad execution"

Not a good idea that never executed at all

What I mean a potential that properly materialized, still gave something amazing, perhaps something so amazing it leaves you yearning for more, something that had so much more to offer but for various reasons, will never FULLY materialize. Perhaps, arguably, for the better, as the idea of it might be better than the reality

Like a lightning in a bottle, you look at all the lightning storms and all the bottles lying around and wonder "all these lightnings and all these bottles to put them in, why is only one bottled in my hands", you will keep looking at bottle in your hand with the lightning, perhaps read that "Lightning in a Bottle 2 confirmed" article from 5 years ago, look at "Spark in a Box" by the guy who bottled the lightning the first time and see the similarities. Yet you will continue to yearn for more lightnings in a bottle.

For me, that is Disco Elysium. An amazing game that I don't think another like it will come or can come. You can call it many different things, a video game, a buddy cop story, a great work about addiction, a criticism of capitalism, a roleplay game, a story, a police drama, a murder mystery, a substance abuse simulator. You can call it many things, but there will never be another thing you can call all these things together.

The lore, the mechanics, the writing, art, voice acting, characters. Just the potential of 1 other story in the same world, using the same tabletop RPG-like mechanics, with entirely different characters, in an entirely different part of the same universe, is huge, only to never be actualized. As far as I know it was in the plans but with everything that happened to company and original crew being scattered, it will never really happen.

Still, Disco Elysium exists, it happened, it can be played, over and over again, experienced as is. And even without its potential fully materialized, what materialized is fucking amazing.