I don't think memorizability (?) is really the issue here, as what he's talking about with the Spencer Mansion and Shadow Moses is a bit different from why he's criticizing modern open world games. Sterling points out how in the last two Far Cry games, the only thing to actually go out and discover are these forgettable, arcade-like minigames with quick and easy objectives. Ex: go kill some defenseless animals with this gun or drive an ATV to that location within 2 minutes. Skyrim and Oblivion may be impossible to memorize but their worlds are filled with hand-placed, and often unexpected, quests and NPCs that stand out from the repetitive side missions that modern games seem to rely on.