I know this feeling - you're climbing up that hill at the very beginning, trying to figure out the mechanics and what the game is about. Then when you finally crest it, you see the whole game set out before you like a beautiful valley... and you realize, "this is going to take hours and days, and I already understand it." You judge the time required vs. the enjoyment that may be gained, and the game loses. And it's sad, because you want the game to win, but you can't just let it.

One game I'll recommend if you're in this boat with me is Slay the Spire - it's a roguelike, so you play run after run from the beginning, instead of working from the same save like Factorio. The mechanics vary from run to run, sometimes significantly, because the cards and relics you collect along the way can completely change how the game plays. I've been enjoying it for a few months now, and while I sometimes put it away for a week or two at a time, I'm still coming back to it. I think part of it is I'm playing to figure out how to survive a run, not to figure out how the game works.

Anyway, check it out - definitely worth $25, and it may give you that long-term enjoyment you're looking for. Though I think, to paraphrase Stand By Me, "I don't have any games like I did when I was 10. Jesus, does anybody?"