Moose 12 runs on Pharo 12 and 13.
It is available in the Pharo launcher as Moose Suite 12 (stable), running on Pharo 12.
To get a local Moose 12 template running on Pharo 13:
Get the file named mysources.list in the assets of this release.
Add it in the root directory for your Pharo launcher (usually named Pharo).
The template image will appear in a dedicated Local Moose entry in your Pharo launcher Image Creation pane