Update: As of September 27, 2018, ISAAC is no longer available on this domain. The links to to it have been removed from the post below, though the remainder of the content has been left unchanged.
ISAAC’s code is still available on GitHub.
The latest, mostly-working version of ISAAC from the development branch on Github can now be found here. This should let you play with the stuff we’re working on right now.
Features here are still undergoing development, though, and are subject to change before a Release. We’ll try to avoid pushing things that are completely broken to this mirror, but there may be minor issues here and there.