Well I did it ... kind of. The initial idea was to beat the game with single coin saving only at the beggining of the level, instead I was saving before bosses as well, and I used second coin to beat alien queen because I couldn't stand the bullshit design.
The final level is really long and hard and fucking cheap ! It's a run for survival basically, you are going to fight a ton of aliens and soldiers, the game will throw everything at you, some enemies that appeared as bosses previously will come back and you will have to kill them several times during this level. You aren't given much of health pick ups either. Ambushes are fucking everywhere and the problem of not being able to fight because there's so much shit on the ground is at it's highest. The quintessence of this crap is, of course, alien queen herself and she's as cheap as her previous incarnation. Hoho it's a final boss, players are feeling the upcoming victory time to milk them for coins !
To start with she can not be hit stunned and that means you are essentially cut off from doing any standing combos because she's just going to hit you back and you can only take like 5 attacks before dying, she also has a lot of hp though developers were king enough to place some powerful weapons nearby, with their help you can deplete like 60% of her health bar but still it's not that simple and in the end you can't really avoid melee. The queen also summons other aliens and oh boy there are a lot of them, yes they have reduced hp (not all of them) but they still inflict full damage and use all of their moves. What's really bad is that queen moves pretty fast so you can't really run away from her and kill other aliens, you also shouldn't lose her from your sight because she has a ranged and a jumping attack which are going to fuck you up if she uses them off screen. Her most devastating attack - tail impale that takes 70% of your health bar, she uses it when she summons her suite, not really hard to avoid but she chases you for a pretty long time which really hampers you when you try to fight off aliens, oh and don't forget the great grab mechanics ! It's so fucking sweet when the horde of xenos drops right on your face, you unwillingly grab one and she immidiately impales you because you are locked in place.
Another problem is that the game features hit stop, it's when you character slows down somewhat when hitting enemies, in the last fight it can fuck you up badly. It's not rare for aliens to stack up in a big pile near the queen and if you do a jumping attack the hit stop is so long that it gives queen enough time to finish the attack that she missed then turn around and smack you.
And the sad thing is that when I used the second coin, I somehow killed her without even putting effort, I was frustrated and wasn't thinking about tactics and she just died pretty quickly, she was almost at full hp when I used additional coin and I only took 2 minor hits. Oh well, really fun game nonetheless, I wish they weren't trying to milk players for tokens though.