Hey @xgomezdans, thanks for tagging! To speak plainly, I archived the repository because it was becoming hard for me to maintain (i.e. maintain even commit-for-commit with pymc3/master), especially with so few users (in fact, I think almost none at all!).
I’d be happy to unarchive and continue maintaining the project, if I was convinced that there were a small but healthy community of users who are earnestly using the software.
Unfortunately, I don’t have the bandwidth to maintain more than just the NUTS/HMC samplers - unless someone would like to contribute to isolate the population samplers, I don’t anticipate littlemcmc offering them anytime soon.