I once encountered a system online, the entire thing was on a single long webpage, and haven't been able to find it since, but I can give you the basics.

Each player was like a "pulp action hero", like Indiana Jones. And each player had already been on some adventures before they joined up for whatever adventure the game would cover.

So I'm creating a character, and I want to be like Indiana Jones, so maybe I'm an Archaeologist. Anything that might be relevant to that skill, I get a bonus (no idea if it was a modifier to beat a DC, or another die to roll to try and get enough successes to succeed at a task; this was a very simplistic system, and that's about all I remember, so the fact that there was a bonus was more important than what it was, you know?)

Then, let's say you and I are creating characters. Well, in the adventure "JHawkInc and the Great Caravan," I spent a lot of time in the desert, and there was this great chase sequence where I evaded some Nazis. So maybe my skills now include "surviving the desert" and "driving." Except you made a cameo in that, so maybe you add in that we escaped the Nazis, the car broke down, and you fixed it. Now I might have a slight bonus to repairing cars, and you could add repairing cars, driving, and surviving the desert as "skills", since you were totally there in my adventure. (or maybe I'm the driver, you're the mechanic, and we both learned some German as our third "skill")

Now we've established a shared adventure and some similar traits between our characters, so we can have callbacks to past adventures the moment we start the game. So now you create an adventure, "Ricecold and the Mystic Mountain" and describe a scenario, skills you gained or used to overcome obstacles, and how it included our buddy Steve. Steve creates an adventure and includes Mark, then Mark creates one and includes me. We've gone around, we all have links to each other though we may not know each other (I don't know Steve, and may not know that you know Mark, at least until we all get going together on a new adventure), and we have a mix of skills with some overlap, and some independent.

And then you go. There was a basic conflict resolution mechanic, and skills could give you bonuses to pass them (though again, can't find the web page, don't remember specifics), and your skills, however broad or narrow they might be, were just about the only things that defined your character. There was some encouragement to let skills bleed over (if you boxed in college it might help you survive a bear attack, or something where your skill could be "kinda" useful), and it was mostly a simple skill system slapped on to give you a mechanic to use while you roleplayed.