Thanks a lot for playing my game and your feedback !
i agree, the rocks are here because they can resolve issue in procedural generation, i tought about remove them.
About the gameplay, as you can see, i want to put some succes in the game, like "finish 10 advanced level" "solve one difficult level in 1:00" ...
And yes, i tought about new style of "exotic" tiles, like city center, mall, ... Each with a specific rule !
I really agree with you, and i'm on my way to improve this game !