Ok, the game is well-made when it comes to the graphics, gameplay etc., but...
I got a crucial issue: a meaning of the game is that you can win it if your skills are good enough, but since - I think - the Aliens are being placed by the game in a completely random way...
The question is: can you be sure that you will win this game after a certain amount of tries or if you don't have luck, you can play it for entire eternity not being able to find the last Alien.
I don't know how many times I returned to this game and still nothing. When oh when the game will decide that I finally deserve to win it?
Answering to one of reviews below you wrote: "If the aliens were too common the excitement of finding a rarer one would be significantly less". Well, when I would finally find the final one, it would not be excitement, it would be nerve exhaustion caused by frustration, something like that and a bit of relief: "It's finally over". I mean it is a bit ridiculous that I am finding an orange legendary one almost every single time now, but cannot find the final Alien. And the game itself isn't doing much to keep you entertained during these more and more repetitive flights.
Oh, one more thing: the Miles and Miles medal is obviously broken.