I doubt they release the source code. You see the whole copyright thingy at the bottom of the page? Tells me they want to sell or make money with the game.

As a hobby coder I create games for myself and I like the challenge to see a feature and then try to recreate it. So that's always the best option in my opinion. But if you can't wait or hit a wall then there are other ways with a bit of googling. Still whatever you find is theirs so to see how it is done might be ok but using their stuff in a copy paste way is really bad. Just a friendly reminder...