Playing on Normal difficulty.

Just got off a quite a session from this where I started from the beginning and managed to pretty much clear the first level. All cameras, hidden spots (afaik) and all that, but then the floor started flooding with the mutants. When I went to the beginning area there were about 8-10 mutants next to the medical machine and everytime I went back to corridors there had been new ones spawning in and just walking from the beginning area to the elevator required me to kill about 6 mutants.

Then, I got to the elevator, headed to second floor and BLAM right outside the door there's a huge pile of probably 10+ mutants ready to take my life virginity. Being cornered I started swinging my trusty lead pipe and managed to kill them all without any huge cut off from my health and things did calm down a bit after that (at least so far I haven't encountered such masses anymore).

Was this some way of the game to "encourage" me to move on? I currently have over 30 stimpacks thanks to all these dumb muties trying to off me. Sadly no screenshots as I was having a bit intense moments there.

welcome in the world of prehistoric games, where everything is difficult and your tears don't matter.

Hah, that's true. However, I just don't remember this happening back when I played this the first times.

Ah, I see. Thank you! Totally forgot about that. Well, it's good that an old game can still keep me on my toes. Rare sight in games these days.

One of my favorite moments was reaching Level 2 - Research and being completely overwhelmed by mutants. Thankfully, I remembered to have a reloaded pistol in my hands as the door opened. :)

To rip and tear through the onslaught of mutants near the elevator, use berserker patch and pipe 'em all.