Some friends and I play multi-world randomizers together. Randomizers modify a game so that important items/unlocks are in different locations or are obtained in a different way. I usually play Ocarina of Time and a randomizer changes all the "treasure chest" items found throughout the world, so instead of finding the bow in the Forest Temple (where it should be in the game), it could be found behind a rock in a cave in the middle of the field. I constantly have to ask myself "What items don't I have yet?" and "What areas do I have access to that I haven't searched yet?" It turns the game into a kind of puzzle game. There is a website we use called Archipelago.gg that lets you connect randomizers together. I can play an OOT randomizer and my friend can be playing a Pokemon Emerald randomizer, and when I open a chest I can find items from his game and he gets a gym badge, an HM, or something else dropped into his inventory. And it works the other way when he beats another trainer, he could get one of my items and I get some rupees, or a hookshot dropped into my inventory.