Maybe that content could be, like you said, more achievements, and maybe that would work just fine, especially with some pleasing feedback as soon as you achieve it.
There is also zero incentive to get premium power ups(power ups that you need to complete advertising tasks in order to get), and that was the only way the game could succeed commercially.
I think I did learn a lot with Dream Catcher, especially on programming. But I don't think I'll really be sure of improvement in the "game design" section until I have actually made a successful game

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