Pretty new to Github and these forums but here’s my attempt to do Tetris alone:
You are close, but it is not a valid sketch in the form:
The folder and the main sketch tab pde file must have the same name, either:
Try downloading it yourself and opening it in Processing PDE to see.
You have also put your sketch into the 2019 branch – not your master branch. That means anyone going to your repo and clicking download will not find they sketch – they will only get the Readme file, which is the only thing in master.
Use git merge (or your desktop tool of choice, I like SourceTree) to merge branch 2019 into branch master.
Thanks for sharing the game!
One suggestion – your pieces freeze the instant that they touch a surface. If you play another Tetris implementation you will often find that there is a short window for sliding left-right, which lets you fit pieces into spots you couldn’t ordinarily reach. So, a piece freezes not when it is first directly above another piece, but when it tries to move into a cell occupied by another piece.