Alien Breed 2 doesn't bother to change things up at all, but its still fun to play.
It still follows the same exact formula, there are about 5 levels, each might take you about an hour to complete if you advance carefully and explore every room. Enemy animations are still somewhat jerky, and hit detection can have a mind of it's own, but if you can look past that, there is a decent twin stick shooter under.
The story still takes place in the same spaceship, so some of the levels will be the locations you visited in the first Alien Breed, but this time mixed around a bit, and probably played in reverse as well, so you might not notice at first but they definitely recycle content.
A new mode is now available, survival. You can pick from up to 3 rooms to struggle against incoming waves of aliens while items and weapons respawn throughout the arena. Apart from those 2 modes there is also a 2 player cooperative mode in which you can explore 3 of the levels from the story mode with a friend, but there still isn't any story coop.
If you liked the first Alien Breed Impact and thought it wasn't enough then you should check out Alien Breed 2 Assault, if you don't mind more of the same that is.