Depends on the game. Depends on the person playing the game.
Yeah, kind of a cop-out answer, but still true.
As for what makes gives a game replayability... I don't really know. For me it's not just a case of whether or not I like the game. For example, take Amnesia: The Dark Descent. I love that game. I think it's brilliant. But I've only played it once and I'll probably never play it again. A lot of what made it so good depended on the player not knowing what was happening or what would happen next.
Yeah, kind of a cop-out answer, but still true.
As for what makes gives a game replayability... I don't really know. For me it's not just a case of whether or not I like the game. For example, take Amnesia: The Dark Descent. I love that game. I think it's brilliant. But I've only played it once and I'll probably never play it again. A lot of what made it so good depended on the player not knowing what was happening or what would happen next.