You might change this
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while (/bin/tetris | grep -v '0 lines'); do; done
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to look like this
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while (/bin/tetris | grep -v '^0 lines'); do; done
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or maybe a space in place of the ^, depending on what it's output looks like. That way it won't have a 10% chance of quitting the loop because you got something like 130 lines (which has the string '0 lines').

--The Amigo