Games that hold their value well over time

With a lot of games, I watch for a sale, and then when I see it I realize that it's just a sign that the price is going to plummet even more. That is part of why anything less than 75% off doesn't really tempt.

However, there are exceptions. Seems to me that Final Fantasy titles, Tomb Raider titles, Far Cry titles, and Total War titles hold onto their value better over time. Often it seems like getting 50% off is maybe the best deal you'll get for even over two years.

Any other titles that seem to hold their value?

Here's a very very very old key for a VERY VERY VERY good game that did not hold its value at all. I?LEL-GT!Q!-BFGGL - ? = How many senses are there? (Not the real or scientific or technical answer, just what we teach grade school children.) ! = How many elements are there? (Think classic games/literature featuring nature mages.) - The key is really old and just may not work. Or it may. I hope it does. The game is very nice.