The original one ran in Internet Explorer. I think the bits are still included in emu/Nt, but

I'd be surprised it if still worked. It was a response to the contemporary "browser as operating system" discussion.

We concluded that if the browser were to provide an operating system, it might as well be a reasonable one

instead of the cruft on offer at the time, and still. Chris Locke quickly did the work.

A similar project for Netscape ran into various problems with the Netscape interface of the time,

and was abandoned, since the whole thing was initially just a bit of fun.