Cool game, but too grindy
The art and the music is quality, and the touch of realism to inhibit super-human player skill was also interesting to explore.
I usually reserve my review space for criticism, so fair warning. This game suffers from programming glitches and gameplay frustrations.
I've already talked about some glitches with you in PMs:
-fake powerups
-permanent powerup zone from the camera's perspective (happens rarely)
-spiders getting stuck in unreachable corners (except the department store level)
-FBI agents getting stuck on ledges and becoming unresponsive
-Pico shooting backwards for no reason
-ducking visual is disjointed with the character's state.
Additional glitches which I'm sure the other reviewers have mentioned are flying up walls due to getting hit by spiders and getting stuck inside them, Pico getting stuck in walking animation sometimes when he hugs the base of a wall (mashing keys fixes it), and lag (I got it constantly on wave 14 and onwards). On exceedingly rare occasions did I manage to fly up walls just by running into them of my own control, and I've also seen FBI agents do the same in one location.
About gameplay, I think the early waves below 8 were okay, given that each wave dispensed a new enemy type until wave 6, and they were of reasonable duration. In this day and age, I think most NGers are a bit too impatient to fully explore a game, but they could be right in that more needs to be done to make the game itself exciting. The aspect of "keep on going until you fail" while not scaling in personal power isn't new, but it can also get to a point where a single mistake can spell your doom.
Beyond wave 8, the number of guys you have to kill quickly get out of control. According to my record, it takes about 1 hour to kill 1000 enemies. Wave 13 has 819 guys, Wave 14 has 1228 guys, and Wave 15 has 1800+ guys. That is just outrageous, and the highest wave highscore tables (if they work at all) are stupid.
Design-wise, I think your game could use a few tweaks. I'm fine with you limiting player superhuman quality by causing delays in his actions and whatnot. But there does come to a point where it's just "really? no really?" Case in point, the most obvious one is turning around. Let's say maybe I trot a few feet, then I decided "oh I don't want to get r4ped by that corridor of spider" and turn around. Takes him .8 seconds to stop, then get going the other way. On the other hand, if I'm in full sprint or I'm in the air, turning around is only a split second. Another case is the distance between the apex of a jump and the landing zone. You really shouldn't have to have a recovery animation if you're hopping up the stairs. It's tedious enough climbing up a floor, nevermind the whole map.
Then there's the monster spawning business. At the beginning of a wave, they should come in gradually, not all at once. I really think it is bullshit approaching a black FBI agent, only to get spazzed on by a solid wall of yellow bullets because said black FBI agent was hiding a bunch of yellow FBI agents. No joke, this really happened. (The other "I can't believe that happened" moment was getting wombo combo'd to death by two spiders closing in on each other, but I can't blame you for that one; extraordinarily unlucky.)
As for the spiders, I've had countless times where I was walking up to one to squish it, only to grow gigantic in size and go "surprise mothanukka I do 250 damage to you!" and my response is "ohgawdhelp". I think it would be nice to either chain stun the spider without interruption, kill it with excessive damage without needing to walk over it, or give a warning clue indicating that it's going to start walking again.
Some final remarks on the game... You could have used more enemy types. There's a lot of different and cool games and movies on Newgrounds that are iconic. And overall, this project seems rushed. It had good potential, but the polish and diversity was lacking.