I would probably add tension, like slowly rising music that when it hits climax, the villain( or antagonist) appears in an epic entrance. Or if from a horror perspective, the antagonist chases the player.
There probably will be Challenging but fun puzzles, not too challenging but enough to keep the player's attention. Finding ways to make subtle but noticable jokes that the player catches would be good too.
(I dunno why but this was fun to write XD)
