onemananadhisdroid
Augur
The weakest of all is actually traditional adventure games, in big parts because it has no core gameplay loop proper to fall back upon should the writing and world building and storytelling department fail (looting, driving your car, blasting demons from hell/Nazi soldiers). A traditional adventure game is really a barebones puzzle skeleton with no much to dress it up. That's both a strength and a weakness depending on the game. If everything goes well, you've got a Grim Fandango. For every Grim Fandango though there had been a hundred Mystery Of The Druids.