From Hard Drop Tetris Wiki
The Eternal Exercise is a stacking challenge where one has to clear a 40L Sprint with only Tetrises, while only keeping a low board (hard stack limit of 15 blocks high). It was originally created by orz while coaching for Underdogs Cup to help newer players practice their upstacking and to document their progress.
The goal of the Eternal Exercise is to help newer players develop fundamental stacking skills by having them only clear Tetrises - this discourages building I dependencies and can allow fine tuning the difficulty of the challenge since players aren't limited to 9-0 stacking, but also 6-3, another popular upstacking style.
- https://jstris.jezevec10.com/usermodes/1699 - The Jstris usermode
- https://web.archive.org/web/20220830153540/https://uc-coaching.herokuapp.com/response - (Web Archive) Underdogs Cup Coaching heroku response page