Game replayability.

[Beware of Cuccos]

I love replaying games I enjoy. To me, it's the same as rereading a very interesting book. Some of my favorites games to replay are-

-Ocarina of Time. It's very interesting to see how many hidden items I can remember on my own, and how many dungeons I can go through without the help of a walkthrough.
-A Link to the Past. Same as above. There are just so many items and sidequests in the Zelda games, I never get bored.
-Banjo-Kazooie. I ALWAYS have a fun time playing this game. By the time I beat it and start over, I forget some stuff, so it's like starting a brand new game.

most of the other games I play aren't really "beatable", such as The Sims and Mario Kart. I know technically you can do a legacy in The Sims, and finish all the races in Mario Kart, but I never play them that way.