For a game made in 48 hours it was good, the monsters speed was pretty slow which allowed me to collect the rocks with no difficulty. The game felt way too easy and at best could have definitely introduced the possiblity of 2 monsters, one near the entrance the other near the end so that you would have to be more conserative of your ammo and how close the monsters are. They also appear too early in the fog and given that the player has aimbot on these monsters pretty much, it basically prevents them from getting too close.
Also instead of feeling right away after collecting more rock samples it should have been a case of taking more bullets. So once you have 5 out of 6 it would take around 3 bullets to make the monster go away. There could've been an ammo amount because this dude apparently just had infinite ammo, probably 30 is all that would have been necessary.
That's just my opinion on what could have been added, the possibility of more lore other than "what happened here was awful" or something along those lines. The game was a pretty short playthrough, the atmosphere was suspensefull, there was very little challenge, the monster was pretty terrifying, not sure what it is but it looked creepy, the PS1 effect definitely contributed to the overall atmosphere of the game.
I'd say this game is a solid 5.5/10 for sure, a lot of improvement could be made but again, for a game made in just 2 days, this is pretty good.