How do I make a zone random generation

Hello,

I am currently making a runner, and I would like to, instead of the default random block generation, do a zone random generation, a bit like "the line zen" does. I mean, I have a lot of different zones wich are composed of different blocks, ennemies and obstacles and that would be chosen randomly.

Example: *youtube.com* /watch?v=qFWBHekMevI

I still need this. Please may someone help me.

Up :s