As I said anything you learn belongs to you to use how you like, within reason, meaning there is a point where all you are doing is spitting out the same code verbatim.
For example, if you mimic every core event, and create the same gameplay with only the graphics changed, then it could be argued that it is nothing more than a reskin.
Basically, memorisation does not constitute learning. Then again, it's not that hard to change a mechanic to make it quite different from the original.
I would wager that you could simply ask here on the forum, and get many suggestions on how to make it more unique.
The licence also covers selling derivatives in the Scirra store, as it's basically reselling a template.
Not only is that bad for the original creator, it also tugs against the terms of one commercial product.
I would add that just making additional features like a leaderboard, or share buttons are not a change to to gameplay.