The perfect list is dependent on what kind of games one likes, and my taste tends to be a bit different than the mainstream. Most of the games I like have one of two things (or both): A good story, or a good sense of place (i.e., I feel like I'm visiting somewhere). With that in mind, here is a list of games that I wished everyone would play and enjoy, but can't guarantee it :)

Zelda Ocarina of Time, Majora's Mask, Windwaker
I think all of these are worth playing for anyone, but if you picked one I would say Ocarina of Time would be the safest bet (many people like the others, but many people also don't). They're famous enough I probably don't have to describe them, but let me just say that in my opinion all of the praise they receive is well-deserved.

Out of this World (Another World)
This is basically a puzzle-solving game, and one that requires trial and error and memorization, so it may not be for everyone. That being said, I love the atmosphere, the sparse story-telling, and the fact that although there are only a few basic controls, most of the game involves thinking outside of the box.
I played this on Sega CD originally, but there is an updated version available: http://www.anotherworld.fr/anotherworld_uk/

Flashback
This is a game by the same person as above, I believe, but it is more action oriented. I'm not sure what someone would think playing it now for the first time, but when it came out I loved the setting and the atmosphere. Probably my favorite game I played on the Sega Genesis.

Day of the Tentacle, Sam and Max Hit the Road, Full Throttle, Monkey Island 1-3, Grim Fandango
I think the only LucasArts adventure game I _didn't_ much like was Monkey Island 4, but the ones listed above are my favorites. All of them have excellent writing and voice-acting (where applicable). I can't imagine anyone not being entertained, although some might not like the gameplay.

Broken Sword 1-3
In the same vein as LucasArts games, but a more realistic setting and serious story. The third one didn't seem to be very-well received, but I loved it. Again, I can see people being turned off by the gameplay, but the story is top notch.

Anachronox
I bought this on a whim, and I will always be glad that I did. The gameplay is actually pretty dumb (it's like poorly-done Final Fantasy), but the story-telling is superb. I don't think I have ever laughed out loud at any game more than I did playing this one.

Ico and Shadow of the Colossus
My two favorite games for the PS2. These games are both so beautiful, both in presentation and mood. Probably the two best games I have ever played in terms of a sense of "place". The story-telling is also very interesting: I would say that both have a good story, but the story is told in a way that would only work in a game. In other words, the plot is not what makes it great, but experiencing it is.

Beyond Good and Evil
This game is great on many levels. The gameplay is fun, but not too hard (this probably annoys hardcore gamers, but for me it's a plus). The graphics are stylized cartoony, but very beautiful, I think. The music is fantastic. I found the story cliche for the most part (towards the end you realize things haven't all been what they seem), but I didn't care because I grew to care about the characters and the world.

Psychonauts
It is a mystery to me why this and Beyond Good and Evil did not sell better. I guess that most people who play games don't like cartoony type art direction. In any event, when I finished this game I said to myself, "why can't all games be more like this?" Again, the game play is fun and not too hard, the graphics are beautiful, the story is original, and the jokes are funny. Also, the different levels are some of the most varied I've seen in one game, and very creative.

Half-Life 2
I loved the first Half-Life, but I think Half-Life 2 set a new standard for games that will be hard to match. Like Shadow of the Colossus, this is a game with a great story that can only be told by experiencing it, rather than being told the plot. I think Half-Life 2 has more "moments" than any other game I've played; you know those times that are so cool that you have a goofy grin on your face and you can't believe how cool it is? Most good games I've played have two or three of those, but it seems like Half-Life 2 consists of them.

Deus Ex
The game that has both excellent story _and_ excellent sense of place! The story is top-notch science fiction / conspiracy theory, and even though the graphics aren't great (especially by today's standards) there is something about the game that really made me feel like I was a part of it. I had an interesting experience: One day I was having a vague memory of being somewhere, but I couldn't place it. I thought and thought about it, trying to remember where it was, and it suddenly hit me that it was a place I had visited in Deus Ex! This game is awesome.

Phoenix Wright: Ace Detective
I would hesitate to put this game in the same category as some of the others I've mentioned, but for some reason I loved it. If you enjoy a good story and don't mind a lack of much gameplay (besides some mental puzzle solving), I would recommend it.

The Longest Journey and Dreamfall
These are two games in a planned trilogy that tell a remarkable story. The plot is very cliched at times, but the characterization is possibly the best of any game I've played. Most people prefer the Longest Journey, but I think Dreamfall is one of the best games I have ever played. If anyone reading this is like me, who is more interested in experiencing a story in a different world than action reflexes, I would recommend in the strongest terms possible checking out Dreamfall. Over and over again while I was playing it, I thought, "Finally someone does this kind of game right!" After finishing it, I read some forums where many people disagreed with me :), but I guess opinions are what makes life interesting.

Morrowind (and maybe Oblivion)
The story in Morrowind isn't much, but the sense of place is unmatched, in my opinion, except by some of the games I've already mentioned. Oblivion is unquestionably prettier, but there's something about Morrowind that I can't explain. It was like visiting a place I had never been before, whereas Oblivion feels familiar and a bit tired. Part of what I enjoyed most about playing was just walking around and looking at stuff. That makes me feel like a total geek, but if you enjoy going on walks or hiking, and want to go on a walk somewhere where you'll never go in real life, consider giving Morrowind a try.

Well, that's probably enough. I realize I have sort of an eclectic taste in games, but there must be some people out there with similar tastes :)
Plus, with some notable exceptions, many of these could be played by older people with encroaching arthritis.

jonpol