I believe The Beatles: Rock Band came the closest to being perfect. Eveything about that game was just beautifully done and the only things missing was Pro Drums, an option for Keys, and a few more Beatle songs (Hey Jude, Strawberry Fields Forever, Yesterday etc. etc.)
I think I would have to go with Stardew Valley. It has something for any mood I’m in.
I can spend my time on the farm, looking after the animals, crops, reorganising. I can go and be social with the neighbours, help them out, do some work towards the community centre. If I feel adventurous I can go explore the mines fighting monsters.
Where I’ve done all that I can start again on a new farm and try a different strategy, I can even play with friends and work together. Its just cozy fun.
Don’t forget the rich modding possibilities and the exhaustive mod landscape.
Gotta be Portal 2. The puzzles are fun, the difficultly curve is reasonable, and the writing is fantastic. Truly the only complaint I have is that I wish there was more of it.
What I really like is that it is never unfair. Once you understand what has to be done, it is easy to accomplish. So it is a great kind of difficulty. And there is more: The free mod “Portal reloaded” is really great.
The 1998 released DethKarz.