Class design

Since i like to reinvent the wheel , i’m still working with awt-swing , studying 2d 3d mini-frameworks,toy games and so on (beside : not bad what you can do in pure java https://www.youtube.com/watch?v=ZV4Dsandc6w).
Long story short : looking for a Tetris tutorial , it seems that the mother of all tuts is the one at
zetcode , the other ones are a copy with some minor tweaks.
A part the fact that this is not a tutorial at all (it’s something like this : you enroll for a painting course , the teacher comes in , gives you a copy of the “Gioconda” , says :
<<Hello guys , here is how to paint>> , and suddenly sails to the nearest pub) i understood nearly all with help of a pencil , some paper and caffeine.
However , in my very humble opinion , the code is stacked in a too huge messy Board class .
I’m wrong ?
Thanks in advance for your opinion…and HAPPY 2018 !
The link :
http://zetcode.com/tutorials/javagamestutorial/tetris/