dk how but I have total dementia of where I played it, what it was called and kind of vividly remember only a single part of it as it really grinded my gears as a kid. it is a 2D flash game which was based in space or Earth with braindead swarms which you had to shoot. the game mostly took place in metallic bunker type areas. it also had a story element to it and I think the characters spoke with textboxes and had their artwork was displayed at either the right or left side depending on whether it was the player character or a NPC. the player character and a few (if not all) wore a kind of armor akin to the Halo spartans but in 2D. there were 2 installments of the game, the second one had the same name w just a 2 appended to it. I love both games dealy but only finished the 1st. my memory is from the 2nd game.
from my recollection the lvl goes like this, the player character is with a female NPC from the same faction inside of an enclosed room inside of a bunker. she is dressed in a similar armor as the main character but w/o a helmet. in prior lvls or the same one she has a gun, which she uses to assist the player in thinning out the enemies. she has a father that has a higher station than both characters. btw she and the main character were kinda a thing. together both the characters plan to escape but their path is blocked a hoarde of enemies that they have to mow down. the objective is to advance through the hoarde and make sure the girl does not die. in my playthrough she died. a lot. when downed she has a health bar that depleates with time or from enemy attacks. idr if there existed a revive mechanic and if it did I was never able to figure it out.
partially restored another memory of a lvl whilst writing. the lvl was a maze with doors. you'd enter through one door and then would be faced with a few more doors. from which you had to find a route to the exit. I do not remember if its a level from the first or the second game, but I think the same NPC was a part of the level and this lvl was the one prior to the one I mentioned above. I am not certain abt this tho.
it has been more than a decade since I last played this game and I've been searching for it ever since. if by sm miracle any1 is able to solve this... I will be forever indebted and grateful. you will be helping a grown man connect with his past and enjoy the joys of his childhood once more. thank you!
Unfortunately I can't help you with the game your looking after since I'm not familiar with that game.
However you could use BlueMaxima's Flashpoint which has filters to sort to all flash games ever made. You might be able to play it there.