After further playing, the only thing saving me from giving this 1 star is how well made the game is in terms of everything except design. The game is impossible to beat, and it is ridiculous that I am expected to beat both a boss and over 15 chaos marines at the same time (chp 2 mission 3).
While I see that submitting to the pay2win would give an advantage, I fail to see how this would come anywhere near to making me beat that mission, let alone the game. Of course, I am only basing this on the advantages that $100 worth would bring. Perhaps the creators expect 200$ instead, likely more.
In the end one has two choices: to pay a ridiculous amount of money (with no guarantee it will allow you to play the rest of the game), or to stop playing. This is not good game design. In fact, this is discouraging and alienating. I hope there will at least be balance changes to the campaign in the future, then Id be both willing to pay and play.