Important: Rules now depends on the latest Typed data API enhancements module, that is alpha1 or the latest development snapshot. If you are updating from a previous Rules version make sure to download and install the Typed Data API module before updating.
Lots of new action and condition implementations, improved usage of the context system and even a minimal UI non-functional prototype. Still quite some stuff to do, see #2245015: [META] Rules 8.x Roadmap.
This release now uses the Context and ContextDefinition classes from Drupal core to implement parameter variables for Rules actions and conditions. It also includes a ProvidedContextPluginInterface to implement provided variables that are produced by an action or a condition.
You can find more information about further plans and achieved goals in the roadmap.
First unstable pre-alpha release of Rules for Drupal 8. This is not usable at all at the moment and is only intended as developer preview. The code mostly consists of bare bones classes with quite a few unit tests, but there is not much functionality implemented yet.