Here’s an interesting one: an unreleased port of an unreleased game.
Yes indeed, Ixion never officially saw the light of day way back when, either in its original arcade incarnation or its home ports. And yet here it is, perfectly preserved in its Atari 8-bit incarnation, all thanks to the efforts of the filthy dirty pirates of the 1980s. Yar-har, fiddle-de-dee.
The game itself is an interesting combination of arena shooter, puzzler and collect ’em up, and I like it very much. If you have an Atari 2600, AtariAge even released an actual physical version of that port — check it out here!