You're looking at StableBuild's Deleted PyPI mirror - where we index all deleted packages from the Python package registry.

mcsq
0.0.0.dev1

This version was deleted from PyPI around 2023-10-08. Installing fails with:
$ pip3 install mcsq==0.0.0.dev1 ERROR: Could not find a version that satisfies the requirement mcsq==0.0.0.dev1
View other deleted versions of mcsq

Install through StableBuild

You can install this package from StableBuild's PyPI snapshots from before the version was deleted:
pip3 install \ -i https://YOUR_API_KEY.pypimirror.stablebuild.com/2023-10-07/ \ mcsq==0.0.0.dev1
Sign up for StableBuild to get an API key (it's free and takes <60 seconds!)

Or, download files manually

And install manually via pip:
mcsq-0.0.0.dev1-py3-none-any.whl (3.6KB)
mcsq-0.0.0.dev1.tar.gz (3.2KB)