I don’t know if the SCI 1 engine is available in its original form on the web somewhere?
Vivendi had nothing to do with it, of course, but there is actually a
freeware SCI editor available at http://www.bripro.com/scistudio/index.php.
I haven’t had time to take a good look at it myself, but according to
the web page it allows users to ‘create games using the
exact same engine Sierra used’.