I'll kind of be quoting good ol' JonTron on this one...or at least making a point that he often makes. This being the sense of child-like wonder when playing a game, either because it introduced a new mechanic or a completely new environment. For me, the perfect example of a game that, when played for the first time, creates this sense of wonder is Yoshi's Island for the SNES.
Honestly, that game was one of the greatest things to come out of the Mario franchise. It had an incredible art style and varying environments. It had so many secrets that you were forced to hug every wall in a level just to make sure you can't go through it. It had some of the most creative bosses ever seen in any game (Not to mention that Bowser's huge form was fucking terrifying.) And it had immersive music to accompany all of this...
Now, creating a sense of child-like wonder is no easy feat. That's obvious. Nowadays it would probably require some serious psychological mind-fucking (Kind of like the Skinner Box but, you know, not evil?). That being said, it wouldn't hurt developers to make their games...different. That's a very broad statement and we could talk about how most Publishers are evil (Because they are) but at least make them subtly different. This goes back to what I said about Yoshi's Island, it was packed with secrets but if you weren't looking for them, you'd be none the wiser about their existence. So packing your game full of subtle detail makes it miles better (Assuming you pull it off right.)
tl;dr Yoshi's Island was fucking awesome, make more games like it.