While the project 'Mirror' aims to address the housing crisis issue which could tangentially relate to societal metacrisis in urban development and living conditions, it is not directly tackling any of the specified metacrisis verticals such as nuclear disarmament, biosecurity, etc. The connection to the horizontal topics like multipolar traps or perverse incentives is also not clear from the provided description. Further information would be required to determine if the communal living solutions proposed by Mirror could be classified under a metacrisis vertical or horizontal.