I am making a small cave copter game (seriously, where did this type of game come from anyway) and I am trying to figure out how to make and store the procedural generated walls. I am thinking about creating the walls by randomly picking two points away from the center of the screen. They will be no closer than the height of helicopter and no further than the edge of the screen, weighted to prefer to go in the same direction as the point prior so I end up with stalactites and stalagmites and not just noise, at set intervals of distance. To store, perhaps parallel arrays/lists, one for distance from center to top screen and one for distance from center to bottom.

Am I way off base with my thinking? I just want the cave to be varied and challenging, I just have never worked with generating data like this.

Edit: Woah, I just realized that my idea would lead to a player being able to stay in the middle of the screen and win. That isn't right at all. So the very basis of how I was going to generate is wrong.

Edit 2: I also realized I left out a very crucial point. Part of the mechanics of the game will let the player go backwards therefor the data structure should be continuous.