This is Time Machine for Atari ST.  It is complete in box, with both game disks, the manual, the anti-piracy notice, and the plastic bag.  The box has some storage wear and deformation, but everything is still in great shape overall.  The game is untested.

Time Machine is an action adventure game that is a bit ahead of its time in some ways.  The game is notable for its use of time puzzles where the player has to use objects in one time period only for it to appear in a later time period, such as a tree growing over time.  This concept would later be used to much acclaim in games like Chrono Trigger and The Legend of Zelda: Ocarina of Time, but Time Machine would beat them to the punch by several years.  Alongside a bit of action and a fun, cartoony sense of energy, Time Machine is quite the enjoyable little game.