Pitching a tabletop game system or 'engine' rather than a specific game
For those of you in the industry, or published designers, I was wondering your thoughts on the idea of pitching to a publisher a game system, with example thematic and play-tested implementations, rather than just a single game?
I've got 3 implementations of the system prototyped, they play in a similar way, but feel like different games because of the thematic differences, different missions and goals for players etc.
I'm wondering whether to pitch each game separately or the entire system for creating the games.