I'd like to design a "bigger" game

I've noticed that all the games I've designed or worked on are "quick fillers" or "medium weight" games. I like to play medium weight games, so it stands to reason that my designs might fall into that category. But I found myself thinking recently that I'd really like to make a game that is heavier and deeper.

I'm not really sure how to go about that. A friend of mine designed Homesteaders, which I find to be pretty deep, lots of emergent strategy. Not really any luck element. That's a really good game, and it's the kind of thing I'm talking about - but I didn't have anything to do with that. I wasn't even involved in playtesting until the game was already mostly finished.

I don't know if any of my current ideas would make for a good heavy game or not - my guess is no, as they are all from before I started thinking about it, and therefore were probably conceived with a 1 hour time frame and "middle weight" in mind. Maybe the Time = Money idea could be interesting enough to warrant a heavyweight game built around it.

I'll have to give it some thought and figure out what exactly I mean by "bigger" or "deeper" or "heavy weight as opposed to medium weight" - then decide how to go about it.