Worst game I've ever played....
Hmmmm...
This is a tough one. I rarely get around to playing games I don't end up enjoying.
The cake-making rythm game on Hello Kitty Bubblegum Girlfriends is probably it for me.
It's like playing guitar hero on expert with the frets randomly swapping places and you can only hit one at a time even when you're meant to hit three, and without an onscreen indicator of when to do so. And three notes missed is game over. Have you ever tried clicking in three places at once with a mouse? I have. It works about as well as you'd expect it to. To this day, my high score is 1.