GALACTIC BATTLE is a space shoot-em up arcade game for one player. Its
setting is an interplanetary spaceship which is controlled by its captain —
you! — against attacks by hordes of evil aliens. Your object in the game is
to defeat as many of the enemy as possible, while enhancing the features of
your ship, and maximizing your score.
This is a great little game. For something that is under 50k zipped it has a lot of levels and options, and at the end of the day it is a fun way to pass a couple of minutes.
Written in 1989, Galactic Battle is a bit like space invaders and runs perfectly on Virtual PC. Grab it from here: http://www.dosgames.com/files/gb.zip