In Alien Hominid Invasion, you can look forward to learning more about what happened to the original alien, where the agents came from, and why there is such an intense hunt for aliens.
The difficulty is modified as well. There is no longer a one-shot kill mechanic - the alien now has a health bar, giving more people the ability to approach the game and fight back against the agents! You can also choose your own difficulty even with playing friends, with the options of Friendly, Normal, and INSANE! Even better, you can choose Mastery mode for extra difficulty.