KT is right not one of the worst sega ports, my mate got this free with an st in 91-92, quite playable and the aliens made a decent mess when blasted and the graphics were drawn reasonably
Samshing aliens all around the world is not so bad task. In fact, it´s a quite pleasant one. About the game what can i say, a sega classic well converted to the atari st obviously some of the arcade stages or enemies blew away and that spooky alien in a spot shape appearing so many times that you can get sick....but well, in general terms is a good game, why not? :)
Certainly not one of the worst of the US Gold/Sega ports but not a really good one either. Still it's playable and the running sections are pretty well done.