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netris – Terminal-based multiplayer Tetris clone
(playnetris.com)
Not the best name, a networked terminal based netris exists since the 90s already: https://salsa.debian.org/rhonda/netris
If it's free and open source and it's also software, it can be discussed here. Subcommunity of Technology.
This community's icon was made by Aaron Schneider, under the CC-BY-NC-SA 4.0 license.