Bugs, glitches, poor AI, boring weapons (and only a handful of them), not much 'alien' stuff to be seen. Forgettable.
The story is very weak. I could describe it in ONE very short sentence, but I don't want to spoil it for the few who might enjoy this mess of a game.
The weapons are so unbalanced and weak that I finished the whole game in one sitting (about five hours!) using only ONE weapon (the same assault riffle you have from the very start). I only changed to the rocket launcher or the sniper rifle when the game forced me to. Otherwise there simply is no point.
You will often encounter portions where you simply don't know what to do next or where the game simply doesn't progress, although you finished all objectives. At one point I had to kill my own character with grenades so I could re-start from the last checkpoint and upon reaching the same point in the game and doing the exact same stuff in the exact same order, the game progressed normally.
You don't get ANY alien-powers, as the few 'aliens' (not really) who appear don't have any special powers or weapons at all.
The game still suffers from terrible slowdowns and runs nowhere near the stable 30fps promised after the technically weak demo released nearly a year ago. It's technically on the same level as said demo.
It all looks OK, but the pretty exterior (the graphics) suffers from a bad interior (the code & story). The game is full of glitches. Just to give you an example: if you die while having the zoom of your weapon enabled, you can't zoom again unless you change the weapon.
The checkpoints are spaced way too far apart, so sometimes you have to replay a two or three minute portion over and over again. The loading times, especially when you've died, are nothing short of horrible. You have the feeling (and it's probably true) that the whole level, including ALL textures and animations is reloaded each time you die.
Do yourself and a favor and forget about this installment. I loved the original "Area 51" on Xbox1, but this game has NOTHING to do with it.