I can figure out my mood by how I play Window's Freecell. I can tell if I'm depressed or if I'm feeling good about myself or what I'm doing by how I play and what my general statistics are. It's pretty interesting.
Theoretically, every Freecell game can be won.
When I'm feeling good about myself and feeling not too tired or not too grumpy or not to angry and depressed about how futile my actions are, I actually play really well. I can get 66%, easy, and during one particularly good week, I had nearly a 90% win rate.
When I'm feeling really depressed I tend to give up far more easily, and I get around a 50% or lower rating. This week I've been around 40%. It's mildly eerie to find a game mirroring my mood, but it makes way too much sense when my lose rate is tightly tied with my perception about whether or not I'm capable of winning.