The Rules module allows site administrators to define conditionally executed actions based on occurring events (known as reactive or ECA rules).
http://d8rules.org/news/d8rules-finishes-milestone-1 presents a nice wrap-up of progress so far as of September 2015. As of November 3, the D8 port is marked as "unstable."
# Project URL
# Where is the code?
# Estimated completion date
Within 3 months, if Milestone 2 funding is achieved. (EUR 14.220 based on the community rate of EUR 45,-) Longer if not.
# Who's doing the port?
# What help do they need?
This initiative is seeking funding to expedite porting efforts. See http://d8rules.org/ for more info.
# D8 roadmap
# Background and reference information