Really nice demo, guns feel good, enemies are creepy and combat is well made. Meatballs are a bit annoying - during the first encounter they spawn a bit too many for too long. They would work better if they were spawned and hurled by some kind of enemy.
A bit too much crawling through pipes - gets old after several attempts on higher difficulty.
Game needs checkpoints throughout the level - wouldn't have to repeat so many crawling sections.
The blade could have a slightly longer reach.
SSG is great, although some kind of visual cue would help indicating when it's ready to fire again. Even as simple as just hiding it down for the duration of the cooldown, like in Dusk.
I would add something to indicate that player is down on health - maybe a heartbeat or slightly pulsating red vignette.
Option to rebind keys would also be nice.