.NET team has just announced that .NET Runtime is open source starting now. You can find the repo on GitHub – here to be precise.
This repo contains an execution engine for .NET apps – this is up-to-date CoreCLR codebase which includes RyuJIT, GC, native interop and plenty of other .NET runtime components. This means that we can fork, clone and build our own version of runtime!
I will keep digging into the details of the repo – until then I highly recommend .NET team blog where you can find more details about the release.