I did not know I could stand on Agro. I did not know I could jump on and hitch a ride on eagles flying past whilst riding Agro. I did not know I could hold on to fish. Yes, after 5 playthroughs in 4 years of Shadow of the Colossus, I had no clue of these things.
Next. FFX. Two collector save files of 100+ hours. Five playthroughs in total. While crafting ultimate armour, why did I go to Omega Ruins to randomly encounter Machea I could bribe instead of just fighting one at the Monster Arena? I don't know. After 6-7 years of FFX, I was still a noob.
So confess! What were/are you oblivious to in the games you play or have played for years?