This is a followup to @SorosFootSoldier@hexbear.net 's recent thread for completeness' sake.
I'll state an old classic that is seen as a genre defining game because it is: Myst. Yes, it redefined the genre... in ways I fucking hated and that the adventure game genre took decades to fully recover from. It was a pompous mess in its presentation and was the worst kind of "doing action does vague thing or nothing at all, where is your hint book" puzzle gameplay wrapped in graphical hype which ages pretty poorly as far as appeal qualities go.
So many adventure games tried to be Myst afterward that the sheer budgetary costs and redundancy of the also-rans crashed the adventure game genre for years.
Hard to feel how bad the combat is in Oblivion when you leave the sewers, dupe glitch some scrolls or potions to sell for enough money to bribe that glitched guy in Imperial City and then use the Lovers daily greater power to paralyze him and take infinite money out of his pocket and then save scum an Oblivion tower to get a Sigil stone that grants Chameleon and then using your infinite money to enchant 4 pieces of equipment with permanent 25% Chameleon and be completely undetectable no matter what forever
IIRC the UOP fixes this