I don't consider myself a gamer — the only console system I ever owned was a Nintendo Entertainment System — but I have in fact devoted significant chunks of my life to video games, most prominent among them the Ultima series. I feel a certain amount of shame around my gaming, maybe because it feels uncomfortably compulsive, and also because it's really not what one is supposed to be doing at work (although, to be fair to myself, I do work hard on everything I'm expected to, and have gone well above and beyond expectations generally).
Nevertheless, with a gaping afternoon of empty hours and a head full of emotional disaster, I have gratefully turned to Jay is Games, an excellent blog and website devoted to "casual gameplay" and the wonderful world of Flash-based gaming.
I've discovered that I'm partial to the point-and-click subgenre, whose games are forgiving of sudden pauses for work, don't call upon too much hand-eye coordination, and give a sense of progress and completion. Favorites include the Hapland, Submachine and especially Samorost series, but I was particularly struck by the intriguing beauty of the Chinese game Choice. It won't take you long, and it really is quite lovely. It helps me get through my day. Maybe it'll help you get through yours.