-The game was released about the mid-90s (TROY was released in '96, that might be a good frame of reference)

-Game had extremely similar graphics to this image, but was a vertically-scrolling space shooter that played like Space Invaders.
-I remember very clearly, that the blue enemies in the middle of the screen were also in it.
-Again, the creator's name is James Saito, but I can't find mention of his old DOS games anywhere on his current site- just the remake of TROY where he just so happened to include a screenshot of the original.
-The only other detail that really comes to mind is that the name has 'Pet' in it somewhere. It wasn't a very long name.