Dune
Dune is an unreleased Atari 2600 prototype that Atari worked on in 1984 to tie in with David Lynch’s film of Frank Herbert’s novel. It was planned as an action-adventure in the style of Atari’s classic Adventure. The version that survives is a very early demo, dated July 1984, with placeholder graphics and unfinished rooms. You can explore it here in your browser, but expect a glimpse of unfinished work, not a complete game.