Here is the list of differences with the final version :
There are ONLY 2 Solar Systems (three in "Gravitar
Different Planet, Bunker and Fuel Cell icons.
Different bunkers' and planets' shapes.
No planet animations.
Stronger and more intense Gravity (Game-play is much harder).
Some sounds are different during the game.
There is an additional 'Low on Fuel' warning if the fuel level drops below 2000 fuel units that is not present in "Gravitar
Rammer ships are present in the south planet of the second solar system - Not in "Gravitar