Andreas Raab writes on the mailing list that:

In its ongoing commitment to Open Source, Qwaq has decided to release the first multi-core capable Croquet VM under the MIT license.

Hydra VM is a virtual machine capable of running multiple Croquet images side-by-side, therefore being able to effectively utilize multi-core CPUs. Hydra VM is still in an early phase of development, but given the (very successful) early results, Qwaq has decided to make it available to general public in the hope that other people will help Igor [Stasenko] to make further progress in developing Hydra VM.