True classic or not (I think it is) if you've finished it go ahead and trade it in. $35 is a great value for that game and it doesn't have any replay value so there's not a lot of sense in keeping it. I personally loved the game to death (my review here) and will probably keep it until I my gaming shelf gets full again and I need to do a clean out, but it wouldn't be one I would be upset to part with. I suppose if I did sell it 6-12 months down the line I would give it another play, but it's still completely sellable. Anyways, I'm rambling. Take the deal.