That being said, I took a look at the code and the way Redux is being used feels kind of weird to me - pretty much a separate reducer for every kind of action.
I think primary focus of this project was to showcase proper Redux implementation. There certainly are much easier ways to accomplish Tetris but that is not what they were shooting for.
Only connecting the root component, fetching the entire state, and passing down all those props manually isn't proper. You shouldn't pass props that can be grabbed directly from the store IMO.
Example: https://github.com/chvin/react-tetris/blob/master/src/reduce...