Strigoi , my ah fellow Internet human I think I remember reading an article about that can't recall whether they made a prototype or if it was just a concept . Please don't tell me they made a prototype because then it will just be another piece of retro gaming epicness I'll never be able to experience . SIGH .
From Wikipedia:
Only five Cosmos units are known to exist
today, three are empty mockup shells and
the other two units are fully functional. One
empty shell and one fully functional unit are
owned by the Atari History Museum, while
the other functioning unit is owned by a
former Atari Inc. employee.
While considered one of the rarest of Atari
Inc.'s unreleased products, one of the
functioning Atari Cosmos has been seen at
several Phillyclassic video gaming shows, as
well as Vintage Computer Fest 3.0. The unit
is set out as part of the Atari History Museum
exhibits run by Curt Vendel, running with
Space Invaders or Asteroids for show-goers to
play.