It's 1979. There's nothing left to be said in the genre of adventure games: empty worlds of puzzles and treasure.

Infocom: let's make an adventure game that emphasizes the emptiness of treasure hunting, and add encounters that can't be solved by victory in combat.

Also Infocom: let's put in all the inscrutable puzzles left over from PDP-10 Zork so the players get their money's worth.