Hello, Sparky!
I 'm kind of working on a project of my own at the moment; but I think the general theme might be a thing you could find useful to focus your skill on.
Have you perhaps considered creating fictional-world 'artefact documents'? That is to say, you design some sort of booklet or chart or other document that would be used by characters within the fictional world. This is by no means a new idea. I myself am inspired by works such as 'Map and Maze Puzzles' ( https://www.goodreads.com/book/show/885275.Map_and_Maze_Puzzles ) and even 'House of Leaves' ( https://www.goodreads.com/book/show/24800.House_of_Leaves ).
That's the 'what'. Now the 'why'.
Imagine you're writing an RPG. There are many interesting systems here on Itch. Each with their own mechanics and requirements. There are some incredible ones that set the game world in a particular way. They feel great because the gimmick is themed in a way that works. Which is nice, but one may wonder if it's possible to keep the same mechanic, but for other settings. Much of the fun of a system depends on what it is that gives the gameplay life.
So then, could it be possible to design your desired game by just focusing on retheming the mechanic somehow, rather than having to also take on some of the other dependencies of their system? If their ideas are too strongly baked into their other mechanics, you're going to need to spend a very long time untangling what it is that makes the system design work when forging your own. Let's use an example; say you read details of some otherworldy RPG with a really good 'suspicion' mechanic. You think "Great! I could use this in my 1920s film noir detective RPG", but then you look again and the thing that made it work in the original was how it had 'secret aliens living in society' ...but still okay, you could shift the time frame and make it a late 1940s and early 1950s detective RPG. Substituting 'secret Communists' as your entity type being the source of the paranoia. You may have to scrap/rethink your 'bootleg liquor' content, but you can work with it. But then you also realise that the threat level of the secret enemy requires paying attention to some ability scores with modifiers. You either don't want ability scores in the very intimate character-driven feel of your RPG, or you have an even better design using skill points. The good idea has come with sets of requirements that make other parts of your game worse. And so you've lost an afternoon trying to make something work, that doesn't.
But then... what if game rules and ideas about how the world works were all modular instead? Rather than having a dry description explaining how time-travel works - players were to hold a document published by an organisation where the workings of time-travel is mentioned.
* You've communicated a concept without having to rely on it always being interpreted the same way. Players have the freedom to critically think about the veracity of the document. The role of the character/s can guide them into what they'll take away from the document (ie. a member of the organisation could believe everything written in it, while a rebel might look for weaknesses to hack into the system.)
* The concept is modular enough that simply by selecting which kind of document you'll reference, you can dramatically set the tone. Such as, a prospectus for shareholders will come across much differently from a pamphlet they give 'time refugees'*. (* that's what I'm currently working on.) This modularity even allows contradictions to be contextual. (eg: different kinds of spellbooks compiled by different sources could mean that there is more than one magic system, or that the different systems are actually different expressions of the same ideas, or perhaps even that one of the systems is a forgery.)
Okay, so... if you're still reading this; perhaps you might find inspiration in recontextualising 'Spellbinder' ( https://mud.co.uk/richard/spellbnd.htm ) into a living document? It's an old game from the 1970s, and it has a lot of potential to be taken further. It can stand alone as an artefact and it's something I was wanting to make, myself, but I'm not as proliferant as I'd like to be.