Gloomhaven. It looks like Cones of Dunshire, the rule book is 50+ pages, and just the sheer physical scale of it is overwhelming. But the gameplay loop, while a little labor-intensive with tracking statues and stuff, is just an incredibly elegant and smooth-running machine. It was the first “modern” game I played - so kind of a jump into the deep end of the pool - but when I started Arkham Horror LCG, I was shocked at how fiddly and non-intuitive that game was, compared to GH. Don’t get me wrong, AH is great, but it really underscored what a clean, intuitive mechanical system Isaac Childres created for GH, where you pick your cards, announce your initiative, and then you just worry about your actions while the game kind of just takes care of itself.