Just to let future interested people know this game is not even beatable on "Easy" without using one or more continues. You'll only get to fight the final boss and get the good ending if you can make it through all 7 levels without dying once wich becomes impossible once you've reached "The Forest". The game will throw so much stuff at you at the same time that dodging becomes simply a matter of luck. The devs really messed up the difficulty in this PC port.

As of today, 09.05.2020 according to the games achievements:

• 1.4 % of all verified owners have beaten this game on the "Easy" mode
• 0.0 % of all verified owners have beaten this game on the "Hard" mode
• 0.0 % of all verified owners have completed the game and recieved the good ending

So nobody has beaten the game yet even on "Easy" without using a continue. Proof that the PC version is way too hard. So hard that it becomes unfair in certain levels (The Forest and The HQ).

Are you sure?
The GOG Database lists two updates in February...

The offline installer files are still at v1.0.2 while on GOG Galaxy v1.0.4 is available. I already informed the GOG support about this but so far nobody seems to really care to update the installer files.

Thanks for the heads-up!

That really sucks.

Unfortunately, since the moment when GOG began to prioritize Galaxy, it's normal to have a delay of months before the update of the offline installers. And that started even before the COVID situation. Sometimes it's more effective to not just inform the GOG support but directly contact the developer as well.

It's worth noting that the achievement for finishing the game on easy is bugged (I just beat it, but it didn't unlock) so the percentage might be a little higher, but yeah, the game is outrageously difficult, I am not even going to try finishing it on hard.

On the plus side, I could use continues AFTER reaching the boss, which makes the last fight super easy (I guess they realized it would drive people insane if they had to play an hour to progress about 1 minute into the boss just to die).

The shooting is fun, and the aliens all die in satisfying ways, but the content is sparse, and the difficulty really puts a damper on it, if you try to reach the ending. If the enemy at least couldn't spawn so close to you (sometimes your character, bodies or enemies hide the spawning until it's too late), if you didn't have to retrieve ammo all the time or if at least the dodge was more forgiving (if you graze a wall, you instantly stop, and the fact that the dodge is so long and you can't change direction mid-roll means ending up on a newly spawned enemy quite often)... Oh well, it's a pity, but what can you do?

Indeed, the game is seriously hard.
I wonder if a gamepad would do any better than pure keyboard. The controls are somewhat clunky, also the menu... took a while until if found a way out of some sub-menus (iirc. it is the "s" key). That's pretty silly, since Esc doesn't work. This is bad porting.
But the difficulty really cuts the fun. Difficult is okay, but if you really have to repeat over and over again with the same starting levels and enemies... uh. Occasionally you see health that you don't need, but later you really crave for some of it, but none will drop. Also the ammunition shortage is quite nasty. The new ammo will appear once you reach something like 15 bullets (which isn't much, esp. later on) and then you have to make your way to the part of the screen where it spawned, through massive hordes.
And I'm playing on easy. :p

It's definitely easier with a contrroller because it's a twin-stick shooter at heart, you got the left trigger for the grenades and the right trigger for the dodge roll, and you can use either the right stick or the face buttons to shoot. It's still fundamentally hard though.

For those who find the game way too hard (and I can't fault them as I'm the saame, the game is super difficult), for an easy copout, you can use cheats and still see the good ending by using the backer menu.

For cheats:
On the main menu, hold LT(L2) + Left + Y (Triangle) and press Start.(Options) while holding the huttons.
With a keyboard, hold Q + W + Left and press Enter while holding the huttons.

For backer menu:
On the main menu, hold LT(L2) + Rigjt + Y (Triangle) and press Start.(Options) while holding the huttons.
With a keyboard, hold Q + W + Right and press Enter while holding the huttons.

On cheat menu enable whatever you want (including the fixed seed so you can practice and learn the patterns if you want).
By selecting Backer #7 you can see the good ending even if you cheat.
By choosing level "The HQ" in both menus you can also cut short on your run time if you just wanna see the ending.

Source: https://www.trueachievements.com/forum/viewthread.aspx?tid=1219688

I don't care about achievements anymore (except maybe in Genshin) so I don't mind never being able to clear everything legit, but I hope it helps.