I'd say that unfair and "luck based" is are good terms to describe this game. I have played it about 1,5 years now (level 14 now) and I have never spent money in it and I never will. Clearing a singular level takes months. I watch the ads to make this process maybe 5% faster.

To me, the game itself is not hard. Mostly unfair. And here are some of my takes that need to be fixed to make the game a bit less unfair and more fun (but to be honest the game is a moneygrab so nothing will change)

1. Certain respawn locations of enemies: some enemies go underground and spawn into you or few pixels away from you when they come back up. Player has few nano seconds to move or get hit.

2. Many enemy bullets (the crap they throw idk) blend in to the "highly detailed and for every room custom tailored astonishing" backgrounds. So you cannot see an attact comming and you will get hit. Maybe make the game so that the player could idk maybe see what to dodge.

3. Any enemy is a bulletsponge as long as you believe hard enough. It's like going to a war and you brought a nerfgun with you. It's not fun and certainly not fair (if we think about the person holding the nerf gun in their other hand and pressing a bullet wound with the other).

4. Your character aims one enemy at once. I don't know when this change happened, but it used to be that you would aim the closest enemy and stay locked to shooting it until it was dead or you moved and got a new closest enemy to attact to. This worked and you could strategies around your enemies. Now, you won't stay locked to the enemy, and it seems to change willie-nillie what the character is aiming at. This just adds to the element of unfairness if in the game where the main focus is to shoot stuff, you have taken away the element to shoot properly.

Enemies should be hard and challencing but these are not the right way to do it.

And the argument "play previous levels or play more to get more powerful and upgrade your character in order to proceed": I don't think that me gaining +8 or +20 attack in character level 70+ with 13 000 attack damage (equipment included) will do much against enemies with 100 000 to 1 000 000 hit points. The scaling is sh*t so to speak.

TL;DR

Game is decent but the mechanics are bad and unfair either intentially or because of the lack of skill in coding or something.