Q is for Qix

My initial introduction to Qix was actually in junior high or high school through a video game strategy book which covered a dozen or so games from the 1980s.  I remember being intrigued by the description of the gameplay as well as the use of the word googleplex, which was used to describe the variation on resultant board patterns which could be seen during gameplay.  Not to mention that the game name actually started with Q, which was rare and which I thought was cool (given my Scrabble playing experiences).

I actually can't remember the place I first found a Qix machine.  I just remember seeing it in an arcade and saying to myself "Hey! There's that cool nerdly Qix game you read about.  Let's try it!"

Suffice it to say, the game is harder than it looks.  It seems on the surface to be some sort of souped up Etch-A-Sketch, but it's a lot harder to draw what you want when you've got enemies chasing you and when the huge Qix is zooming around the screen randomly (though always seeming to want to go at you).  Playing the game was always quite a workout as well, because you had to follow the contours of the filled-in screen if you weren't in the process of drawing a line, and I remember my arm being tired after a few games.

What games have you played that had a seemingly simple premise but when played turned out to be more complicated than was evident on the surface?