Same issue I reported for castersoundboard. Depends on ubuntu-core but ubuntu-core is deprecated in favour of core.
warzone2100
cannot locate the base snap: ubuntu-core: No such file or directory
snap install ubuntu-core error: cannot install “ubuntu-core”, please use “core” instead
snap list
Name Version Rev Developer Notes
castersoundboard 0+git.c41a4f2 34 rikai -
core 16-2.26.14 2462 canonical core,devmode
warzone2100 3.2.3 5 diddledan -
EDIT: For Reference