Tetris Effect: Connected

If you're high like me, this might seem tricky. However, if you go into effect mode from the main menu and scroll down to the All Clears stage, you can get constant clears. All Clears mode is like a puzzle, they give you the pieces and a garbage looking board and ask you to finish it. Some of them are easy, others not so much.

With the puzzles that are all lines only, you can also work on your back to backs with them.