Chrono Trigger. Considering it's the only game I will take time to play every year no other game can come close to being my favorite.
Don't really have a favourite game but enjoy the Metro series (2033 & LL), GTAV obviously, and Alien Isolation
May sound unrealistic, but my fav games are GTA: San Andreas and Need For Speed Underground 2. Those had marked my infance!
Star Craft - Broodwar (Can't believe there aren't more of you that don't like it!? What's wrong with you guys??? ) Oh... and a really cool but long obsolete Hoyle game package. (I think it was a Windows ME version). Simple but a great alternative to quicky-games like Spider Solitaire and the like. It's on my to-do list to offer it here once I can figure out how to properly present it.
I like OpenTTD. Grew up playing Transport Tycoon Deluxe (TTD) and when it became abandoned, the guys from OpenTTD took over. Now it has tons of new features, heavily optimized and also exists in x86 and x64. And is portable too, gotta love that.