/usr/share/games/BlocksOfTheUndead/assets/lvls/ is in blocks-of-the-undead-data 1.0-6.
This file is owned by root:root, with mode 0o755.
..
/usr/share/games/BlocksOfTheUndead/assets/lvls/1/
/usr/share/games/BlocksOfTheUndead/assets/lvls/1/1.txt
/usr/share/games/BlocksOfTheUndead/assets/lvls/1/2.txt
/usr/share/games/BlocksOfTheUndead/assets/lvls/1/3.txt
/usr/share/games/BlocksOfTheUndead/assets/lvls/1/4.txt
/usr/share/games/BlocksOfTheUndead/assets/lvls/1/5.txt
/usr/share/games/BlocksOfTheUndead/assets/lvls/1/6.txt
/usr/share/games/BlocksOfTheUndead/assets/lvls/2/
/usr/share/games/BlocksOfTheUndead/assets/lvls/2/1.txt
/usr/share/games/BlocksOfTheUndead/assets/lvls/2/2.txt
/usr/share/games/BlocksOfTheUndead/assets/lvls/2/3.txt
/usr/share/games/BlocksOfTheUndead/assets/lvls/2/4.txt
/usr/share/games/BlocksOfTheUndead/assets/lvls/2/5.txt
/usr/share/games/BlocksOfTheUndead/assets/lvls/2/6.txt
/usr/share/games/BlocksOfTheUndead/assets/lvls/3/
/usr/share/games/BlocksOfTheUndead/assets/lvls/3/1.txt
/usr/share/games/BlocksOfTheUndead/assets/lvls/3/2.txt
/usr/share/games/BlocksOfTheUndead/assets/lvls/3/3.txt
/usr/share/games/BlocksOfTheUndead/assets/lvls/3/4.txt
/usr/share/games/BlocksOfTheUndead/assets/lvls/3/5.txt
/usr/share/games/BlocksOfTheUndead/assets/lvls/3/6.txt