Maybe some super-simple casual game, or some interactive story. Something where the active gaming part is minimized to the minimum, and which I wouldn't necessarily consider as a proper game at all normally.

If I am down and/or mentally tired, I usually don't really feel like playing because I consider it a mental activity that requires pretty good concentration. Most probably I'd choose something less burdening like watching a movie or TV series. If I am _really_ down, even they might feel too much, e.g. remembering when I was told as a kid that someone close to me is going to die, I didn't even want to watch Rambo 3 from video with a friend of mine. I just wanted to lie on the bed and go through things in my head.

Gaming is much more often to me either:

- fighting boredom, ie. I do want to do something that activates me

- trying to escape boring duties and boring real life

Come to think of it, so is internet. Internet surfing as an activity is to me something between gaming and passively watching TV.

Postal 2. It just makes me smile :)

Anything I can play while really drunk. Usually something not serious, like a XBLA type title (Warped, Death Spank, etc.).

Several NES games do that for me. Mega Man 2, 3, Zelda 1, Mario 1, 3

If I'm bored and have no idea what to play, anything with an NES emulator on it and those games works for me.

When I'm down there is really nothing better to play that some Ethnic Cleansing. Cheers you up immediately.

The champ flood will always catch the noobs off guard. They can never understand why you'd pick the Goths, "But they can only build wooden walls!" Lol!

My pick is Hitman. Depending on my mood, I either go guns blasting or snipe everyone.

Stronghold always brings me peace. Or the original Majesty.

Day of Defeat for some odd reason and Postal 2 usually cheer me up.

One time I came home drunk and played emulated Rygar and then Rush'n Attack. It cheered me up.

Assassins Creed...

I sit there at a vantage point and just relax... walk along the river banks, just enjoy the sites and sounds... Honorable mentions would be: Quake 2/4 and Unreal

All of them. :)

Myst. It's like instant relaxation. Also Skyrim, for pretty much the same reason.

I guess the closest thing I have to this is Minesweeper. I have it on my phone, so it's accessible pretty much all the time. Since I've gotten to the point where I don't really need to think about it to play it, I can usually just relax and start pressing around on the screen. In fact, I usually get my best times when my mind is almost completely focused on something else.

Doom, Dungeon Keeper, Commander Keen, Command & Conquer.