From the back of the box ...
"Deep inside the granite mantle of the Earth, there is an evil so great that man dares not speak the word. Only whispers have filtered out into the land of the living. The warlords of KRALTHA dominators of the inner Earth, have constructed a prison so deadly, so filled with danger and loathsome mutants, that all who have attempted to penetrate the secrets of FORT APOCALYPSE have vanished without a trace. "
Flying a helicopter you must ...
"... descend through the KRALTHAN DISRUPTOR fields, capturing weapons and fuel, and freeing the enslaved masses. Past the disruptor fields, the danger grows in the VAULTS of DRACONIS, where the very granite is locked in a temporal matrix. Then swiftly, ever so swiftly, you descend into the ROTATING FIELD-ENVELOPE, where time itself is scarred and twisted back on itself. "
In addition to peppering the back of this box with UNNECESSARY CAPITALIZATION, Synapse software produced a variety of games for the Atari family of computers. They released their games in cartridge, disk and tape formats. They specialized in arcade style adventure games. This game is a lot of fun.
The package is complete. Instructions are present in the box