Here's an interesting question I saw on reddit a few nights a go.
If you could forget everything about one game, so you could re-experience it, which game would it be?
For me it would be Half-Life 2. I remember playing through it for the first time as a 13 year and was amazed. Hell I still am amazed at everything it did, from the story to the gameplay mechanics. I'd love to re-capture that magic from when I played as a 13 year old.