The best immersive 'sticky' is when contributions twine about each other like a wild tanglevine, each hopefully adding some substance to the other.
So how difficult would this be? A complete Lexicon would take twenty-six 'turns'. Most games seem to be set up to provide a turn a week. Would six months be too long for a backstory setup? Mmm. If even five people worked at it: the seed would have 130 entries and be an interesting artifact.
There would be no commitment from You to play a rpg based on Yianeveh. Nor would there be a guarantee from me of running such. Mmm. That's probably a broken equation. Why would folks commit to entries if the only result was a wiki artifact? Then again, Lexicon Games are writing puzzles that appeal to me.
Perhaps. Just a blip: Yianeveh, at the seed wiki.