Make it through a Myst game without consulting a strategy guide.
Finally did it with Myst III not too long ago. Long enough after playing through it the last time that I barely remembered any of it, so prior experience didn't help me very much. In fact, I distinctly remember getting through the Edana Age with no problem the first time I played it, and I got stuck in so many places this time around it wasn't even funny.
And I wanted to punch myself in the face for over-complicating the Amateria ball and weight puzzle as much as I did. It was the ONE puzzle I consistently needed a guide for, and then this time, "Oh my frickin' god... Was it seriously THAT simple!? THANK YOU, ELEMENTARY SCHOOL PHYSICS."