Amazing work, I am impressed. However the Tetris is not the ideal game for e-ink display. I hope you are going to port another games :-). I would really like to see puzzle games in it - a sokoban game for example.
Another interesting application would be a gamebook-player. I have created html versions of some of my childhood-favorite Fighting Fantasy books, converted them to epub, it is really fun to replay those books nearly 30 years later on my Kobo - and tapping a link is much more comfortable than turning pages several times a minute. However the pen-and-paper statistics and a dice are still mandatory to enjoy them: these could be replaced by a python app...