It takes a very special game to give you so much to learn, so many ways to do everything, that even after 1000 hours of playtime you still feel like a beginner. Factorio is daunting in the extreme, and I remember bouncing off it the first time I tried. Thank goodness I gave it a second chance. Building up a gigantic world-spanning, atmosphere-destroying factory slowly and methodically over dozens of hours is probably my favourite singleplayer experience in games.
Thing is, nowadays Factorio is far from the only factory-building game out there. Many have followed in its footsteps - most notably, the excellent Satisfactory and Dyson Sphere Program. So what keeps me coming back to Factorio after all this time?
Ironically for a game that essentially is about destroying an ecosystem for selfish gain, it's all about the quality of life features. Such a ridiculous amount of time must have been spent at Wube headquarters thinking about how to make life easier for the player. More than any other game, Factorio has so many little tiny extra features that after several hundred hours make you go, "Oh my god, you can do that? Oh, that's fantastic. That's gonna make things so much more efficient. Oh, that's good." And I'll spend the rest of the afternoon occasionally shaking my head in faint disbelief at the stupendous genius of the minds behind Factorio.
I suppose you could argue that it's not exactly a good thing that it takes hundreds of hours before you realise that there's an easier way of doing a thing. But if you know Factorio, you'd understand. The tutorial does the best it can, but the game is so incredibly ambitious in scope, there's far, far too much to learn to fit it all into a tutorial. It's all about trying things out and discovering everything for yourself.