The assets themselves are fine, and I can see the marathon inspiration, which is really cool, I dig it. But unfortunately it's not fun to play. Fist can stunlock the spear alien, but then there's no point in it when the pistol has infinite ammo. Regenerating health made me not care about avoiding homing projectiles at all. Couldn't change the difficulty in-game, so maybe that's because I was playing on normal?
The map feels empty. I used the map, and it helps, but there's no life. Like - the decorated parts of the map are fine and give you the idea of what's the place supposed to be - like the office cubicles, or the infirmary, but then right next to that decorated room is a huge empty area.
Aliens don't feel threatening due to regenerating health. Rifle is fine, but ran out of bullets in the same room where I acquired it - had to finish off the crowd with a pistol. And that was the most fun I had, since otherwise I had to fight like 2 or 3 aliens at a time, and they were no threat at all.
The map itself would've been fine for a doom-style slaughtermap, but it wasn't that, unfortunately. And balance definitely needs some fine-tuning.
And if you're going for an old style FPS - please, please get rid of the regenerating health, it completely kills any sort of challenge.