I don't know if it's just me, but I tend to have a go-to game. As in, if I feel really bored and have nothing to do, maybe feel a bit down, I play a certain game to cheer me up. Sure, there are many go-to games I could use, but one is more prominent than the others and is used more often, and that would be Super Mario 64. I always have a good time with it.

What about you guys?

P.N.03 - it's difficult to stay bored when my pants are angry.

Chrono Trigger...never gets old!

Definitely Flower. Playing the first level is always a good way to cheer myself up, the serenity and calm of it really just gets to you.

Flower also works for me, I love every level except the last one and could play them over and over.

Nowadays: a BIT.TRIP game or an Art Style game.

All time: Super Mario Bros. I have to beat it a few times a year. I usually speedrun the game, but sometimes I want to explore worlds 6 and 7 and it gets really crazy.

Lmao! It's a fun game too.

My game is Resident Evil 4 or Ocarina of Time or Fallout 3 or Halo or Mario Kart: Double Dash!!. Any game in my top 5.

Starcraft 2

Many years ago that role was perfectly done by Wave Race 64 and Pilot Wings 64. The analog stick felt so great in those games!
Nowadays I am not sure I have a go to game. There are so many out there that I want to play and I have so little time to do so...
But I guess that might be among PES 2009, Guitar Hero 3 and Wii Sport Resort.

LittleBigPlanet and Mario Galaxy. Instant pick up and play fun! And they never get old.