Easy one - right answer is Botanicula! :)

https://www.youtube.com/watch?v=UxeaS4Pq4EY

:0

The final level of Immortal Defense
Trine
Sorcery! (steam)
Tales of Maj'Eyal (temporal warden)
Death Knights of Krynn
Hollow Knight (although I got bored eventually)

Stardew Valley stresses me a lot, and when it stops doing so (typically by spring 2, as the main challenge comes from finishing the greenhouse in time for winter), I get bored and stop playing.

Chuchel.

I gave it another try for a couple of hours today.

I had forgotten. I can;t physically do the fishing portion of the game.

edit: There's an autofish plugin. I;ll have to try it tomorrow.

Depends on what you mean by 'happy'.

Generally progress without being annoying, and where i don't lose much, especially by crappy RNG.

Not too much grind as to get bored/disinterested.

Regardless here's some games i've found fun and made me happy: RingRunner, Megaman X, TIS-100, MagicMaker, Spaz (especially with mods to try), Nier Automata, Tyrian, Android Cactus, Rebel Galaxy, some Final Fantasy games, Xixit.... Oh yes Xixit....

Fishing is a bitch but does get easier with better gear.

Doom 1 & 2 are my 'comfort food' of video games.

The Pirate Doom mod in particular is pure bliss.

The Legend of Kyrandia 2: Hand of Fate
Tales from the Borderlands

Euro Truck Simulator 2 (on Steam) is pretty therapeutic. Pick an internet radio station with some funky tunes for your mood, start your engine, pick up thirty tonnes of digger, set your sat-nav or brave it with the good old map-and-luck technique, and enjoy the long haul through mainland Europe all the way to Swansea. Drop off the JCB, get a container of rice from the docks and head right back.

That game helped me get my BA thesis done and introduced me to some decent music. I think it's just what I need right now, come to think of it.

Theme Hospital.

Soccer Kid

Broken Sword series;)