He he he, I dug up this ancient post and I felt I just had to answer it!
Mosaic was a 3D game that Jason Jones was working on in late 1993, he stopped work to be able to fully concentrate on Marathon. "All that is known about Mosaic is that it had nothing to do with the web browser of the same name and that Jason is extremely reluctant to discuss it."
But, um... Knowing this, don't you guys feel an urge to find out what it is? Personally, I really need to know. Maybe Bungie are going to hide an early pre-alpha version of it on the Halo CD! Would be neat. I hope you're listening, Jason! I also hope it still exists on some old disk somewhere...
